| Message ID | 817eae486273adad0a622671f628c5a99b72a375.1620200410.git.kai.huang@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | TDP MMU: several minor fixes or improvements | expand |
On Wed, May 5, 2021 at 2:38 AM Kai Huang <kai.huang@intel.com> wrote: > > TDP MMU iterator's level is identical to page table's actual level. For > instance, for the last level page table (whose entry points to one 4K > page), iter->level is 1 (PG_LEVEL_4K), and in case of 5 level paging, > the iter->level is mmu->shadow_root_level, which is 5. However, struct > kvm_mmu_page's level currently is not set correctly when it is allocated > in kvm_tdp_mmu_map(). When iterator hits non-present SPTE and needs to > allocate a new child page table, currently iter->level, which is the > level of the page table where the non-present SPTE belongs to, is used. > This results in struct kvm_mmu_page's level always having its parent's > level (excpet root table's level, which is initialized explicitly using > mmu->shadow_root_level). This is kinda wrong, and not consistent with > existing non TDP MMU code. Fortuantely the sp->role.level is only used > in handle_removed_tdp_mmu_page(), which apparently is already aware of > this, and handles correctly. However to make it consistent with non TDP > MMU code (and fix the issue that both root page table and any child of > it having shadow_root_level), fix this by using iter->level - 1 in > kvm_tdp_mmu_map(). Also modify handle_removed_tdp_mmu_page() to handle > such change. Ugh. Thank you for catching this. This is going to take me a bit to review as I should audit the code more broadly for this problem in the TDP MMU. It would probably also be a good idea to add a comment on the level field to say that it represents the level of the SPTEs in the associated page, not the level of the SPTE that links to the associated page. Hopefully that will prevent similar future misunderstandings. > > Signed-off-by: Kai Huang <kai.huang@intel.com> > --- > arch/x86/kvm/mmu/tdp_mmu.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c > index debe8c3ec844..bcfb87e1c06e 100644 > --- a/arch/x86/kvm/mmu/tdp_mmu.c > +++ b/arch/x86/kvm/mmu/tdp_mmu.c > @@ -335,7 +335,7 @@ static void handle_removed_tdp_mmu_page(struct kvm *kvm, tdp_ptep_t pt, > > for (i = 0; i < PT64_ENT_PER_PAGE; i++) { > sptep = rcu_dereference(pt) + i; > - gfn = base_gfn + (i * KVM_PAGES_PER_HPAGE(level - 1)); > + gfn = base_gfn + i * KVM_PAGES_PER_HPAGE(level); > > if (shared) { > /* > @@ -377,12 +377,12 @@ static void handle_removed_tdp_mmu_page(struct kvm *kvm, tdp_ptep_t pt, > WRITE_ONCE(*sptep, REMOVED_SPTE); > } > handle_changed_spte(kvm, kvm_mmu_page_as_id(sp), gfn, > - old_child_spte, REMOVED_SPTE, level - 1, > + old_child_spte, REMOVED_SPTE, level, > shared); > } > > kvm_flush_remote_tlbs_with_address(kvm, gfn, > - KVM_PAGES_PER_HPAGE(level)); > + KVM_PAGES_PER_HPAGE(level + 1)); > > call_rcu(&sp->rcu_head, tdp_mmu_free_sp_rcu_callback); > } > @@ -1009,7 +1009,7 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, > } > > if (!is_shadow_present_pte(iter.old_spte)) { > - sp = alloc_tdp_mmu_page(vcpu, iter.gfn, iter.level); > + sp = alloc_tdp_mmu_page(vcpu, iter.gfn, iter.level - 1); > child_pt = sp->spt; > > new_spte = make_nonleaf_spte(child_pt, > -- > 2.31.1 >
On Wed, May 5, 2021 at 9:28 AM Ben Gardon <bgardon@google.com> wrote: > > On Wed, May 5, 2021 at 2:38 AM Kai Huang <kai.huang@intel.com> wrote: > > > > TDP MMU iterator's level is identical to page table's actual level. For > > instance, for the last level page table (whose entry points to one 4K > > page), iter->level is 1 (PG_LEVEL_4K), and in case of 5 level paging, > > the iter->level is mmu->shadow_root_level, which is 5. However, struct > > kvm_mmu_page's level currently is not set correctly when it is allocated > > in kvm_tdp_mmu_map(). When iterator hits non-present SPTE and needs to > > allocate a new child page table, currently iter->level, which is the > > level of the page table where the non-present SPTE belongs to, is used. > > This results in struct kvm_mmu_page's level always having its parent's > > level (excpet root table's level, which is initialized explicitly using > > mmu->shadow_root_level). This is kinda wrong, and not consistent with > > existing non TDP MMU code. Fortuantely the sp->role.level is only used > > in handle_removed_tdp_mmu_page(), which apparently is already aware of > > this, and handles correctly. However to make it consistent with non TDP > > MMU code (and fix the issue that both root page table and any child of > > it having shadow_root_level), fix this by using iter->level - 1 in > > kvm_tdp_mmu_map(). Also modify handle_removed_tdp_mmu_page() to handle > > such change. > > Ugh. Thank you for catching this. This is going to take me a bit to > review as I should audit the code more broadly for this problem in the > TDP MMU. > It would probably also be a good idea to add a comment on the level > field to say that it represents the level of the SPTEs in the > associated page, not the level of the SPTE that links to the > associated page. > Hopefully that will prevent similar future misunderstandings. I went through and manually audited the code. I think the only case that needs to be added to this is for nx recovery: --- a/arch/x86/kvm/mmu/tdp_mmu.h +++ b/arch/x86/kvm/mmu/tdp_mmu.h @@ -31,7 +31,7 @@ static inline bool kvm_tdp_mmu_zap_gfn_range(struct kvm *kvm, int as_id, } static inline bool kvm_tdp_mmu_zap_sp(struct kvm *kvm, struct kvm_mmu_page *sp) { - gfn_t end = sp->gfn + KVM_PAGES_PER_HPAGE(sp->role.level); + gfn_t end = sp->gfn + KVM_PAGES_PER_HPAGE(sp->role.level + 1); /* * Don't allow yielding, as the caller may have a flush pending. Note, Otherwise we won't zap the full page with this change, resulting in ineffective or less reliable NX recovery. > > > > > Signed-off-by: Kai Huang <kai.huang@intel.com> > > --- > > arch/x86/kvm/mmu/tdp_mmu.c | 8 ++++---- > > 1 file changed, 4 insertions(+), 4 deletions(-) > > > > diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c > > index debe8c3ec844..bcfb87e1c06e 100644 > > --- a/arch/x86/kvm/mmu/tdp_mmu.c > > +++ b/arch/x86/kvm/mmu/tdp_mmu.c > > @@ -335,7 +335,7 @@ static void handle_removed_tdp_mmu_page(struct kvm *kvm, tdp_ptep_t pt, > > > > for (i = 0; i < PT64_ENT_PER_PAGE; i++) { > > sptep = rcu_dereference(pt) + i; > > - gfn = base_gfn + (i * KVM_PAGES_PER_HPAGE(level - 1)); > > + gfn = base_gfn + i * KVM_PAGES_PER_HPAGE(level); > > > > if (shared) { > > /* > > @@ -377,12 +377,12 @@ static void handle_removed_tdp_mmu_page(struct kvm *kvm, tdp_ptep_t pt, > > WRITE_ONCE(*sptep, REMOVED_SPTE); > > } > > handle_changed_spte(kvm, kvm_mmu_page_as_id(sp), gfn, > > - old_child_spte, REMOVED_SPTE, level - 1, > > + old_child_spte, REMOVED_SPTE, level, > > shared); > > } > > > > kvm_flush_remote_tlbs_with_address(kvm, gfn, > > - KVM_PAGES_PER_HPAGE(level)); > > + KVM_PAGES_PER_HPAGE(level + 1)); > > > > call_rcu(&sp->rcu_head, tdp_mmu_free_sp_rcu_callback); > > } > > @@ -1009,7 +1009,7 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, > > } > > > > if (!is_shadow_present_pte(iter.old_spte)) { > > - sp = alloc_tdp_mmu_page(vcpu, iter.gfn, iter.level); > > + sp = alloc_tdp_mmu_page(vcpu, iter.gfn, iter.level - 1); > > child_pt = sp->spt; > > > > new_spte = make_nonleaf_spte(child_pt, > > -- > > 2.31.1 > >
On Wed, 2021-05-05 at 10:01 -0700, Ben Gardon wrote: > On Wed, May 5, 2021 at 9:28 AM Ben Gardon <bgardon@google.com> wrote: > > > > On Wed, May 5, 2021 at 2:38 AM Kai Huang <kai.huang@intel.com> wrote: > > > > > > TDP MMU iterator's level is identical to page table's actual level. For > > > instance, for the last level page table (whose entry points to one 4K > > > page), iter->level is 1 (PG_LEVEL_4K), and in case of 5 level paging, > > > the iter->level is mmu->shadow_root_level, which is 5. However, struct > > > kvm_mmu_page's level currently is not set correctly when it is allocated > > > in kvm_tdp_mmu_map(). When iterator hits non-present SPTE and needs to > > > allocate a new child page table, currently iter->level, which is the > > > level of the page table where the non-present SPTE belongs to, is used. > > > This results in struct kvm_mmu_page's level always having its parent's > > > level (excpet root table's level, which is initialized explicitly using > > > mmu->shadow_root_level). This is kinda wrong, and not consistent with > > > existing non TDP MMU code. Fortuantely the sp->role.level is only used > > > in handle_removed_tdp_mmu_page(), which apparently is already aware of > > > this, and handles correctly. However to make it consistent with non TDP > > > MMU code (and fix the issue that both root page table and any child of > > > it having shadow_root_level), fix this by using iter->level - 1 in > > > kvm_tdp_mmu_map(). Also modify handle_removed_tdp_mmu_page() to handle > > > such change. > > > > Ugh. Thank you for catching this. This is going to take me a bit to > > review as I should audit the code more broadly for this problem in the > > TDP MMU. > > It would probably also be a good idea to add a comment on the level > > field to say that it represents the level of the SPTEs in the > > associated page, not the level of the SPTE that links to the > > associated page. > > Hopefully that will prevent similar future misunderstandings. > > I went through and manually audited the code. I think the only case > that needs to be added to this is for nx recovery: > > --- a/arch/x86/kvm/mmu/tdp_mmu.h > +++ b/arch/x86/kvm/mmu/tdp_mmu.h > @@ -31,7 +31,7 @@ static inline bool kvm_tdp_mmu_zap_gfn_range(struct > kvm *kvm, int as_id, > } > static inline bool kvm_tdp_mmu_zap_sp(struct kvm *kvm, struct kvm_mmu_page *sp) > { > - gfn_t end = sp->gfn + KVM_PAGES_PER_HPAGE(sp->role.level); > + gfn_t end = sp->gfn + KVM_PAGES_PER_HPAGE(sp->role.level + 1); > > /* > * Don't allow yielding, as the caller may have a flush pending. Note, > > Otherwise we won't zap the full page with this change, resulting in > ineffective or less reliable NX recovery. Oh correct. I missed this. I'll add this in next version. Thanks. > > > > > > > > > Signed-off-by: Kai Huang <kai.huang@intel.com> > > > --- > > > arch/x86/kvm/mmu/tdp_mmu.c | 8 ++++---- > > > 1 file changed, 4 insertions(+), 4 deletions(-) > > > > > > diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c > > > index debe8c3ec844..bcfb87e1c06e 100644 > > > --- a/arch/x86/kvm/mmu/tdp_mmu.c > > > +++ b/arch/x86/kvm/mmu/tdp_mmu.c > > > @@ -335,7 +335,7 @@ static void handle_removed_tdp_mmu_page(struct kvm *kvm, tdp_ptep_t pt, > > > > > > for (i = 0; i < PT64_ENT_PER_PAGE; i++) { > > > sptep = rcu_dereference(pt) + i; > > > - gfn = base_gfn + (i * KVM_PAGES_PER_HPAGE(level - 1)); > > > + gfn = base_gfn + i * KVM_PAGES_PER_HPAGE(level); > > > > > > if (shared) { > > > /* > > > @@ -377,12 +377,12 @@ static void handle_removed_tdp_mmu_page(struct kvm *kvm, tdp_ptep_t pt, > > > WRITE_ONCE(*sptep, REMOVED_SPTE); > > > } > > > handle_changed_spte(kvm, kvm_mmu_page_as_id(sp), gfn, > > > - old_child_spte, REMOVED_SPTE, level - 1, > > > + old_child_spte, REMOVED_SPTE, level, > > > shared); > > > } > > > > > > kvm_flush_remote_tlbs_with_address(kvm, gfn, > > > - KVM_PAGES_PER_HPAGE(level)); > > > + KVM_PAGES_PER_HPAGE(level + 1)); > > > > > > call_rcu(&sp->rcu_head, tdp_mmu_free_sp_rcu_callback); > > > } > > > @@ -1009,7 +1009,7 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, > > > } > > > > > > if (!is_shadow_present_pte(iter.old_spte)) { > > > - sp = alloc_tdp_mmu_page(vcpu, iter.gfn, iter.level); > > > + sp = alloc_tdp_mmu_page(vcpu, iter.gfn, iter.level - 1); > > > child_pt = sp->spt; > > > > > > new_spte = make_nonleaf_spte(child_pt, > > > -- > > > 2.31.1 > > >
On Wed, 2021-05-05 at 09:28 -0700, Ben Gardon wrote: > On Wed, May 5, 2021 at 2:38 AM Kai Huang <kai.huang@intel.com> wrote: > > > > TDP MMU iterator's level is identical to page table's actual level. For > > instance, for the last level page table (whose entry points to one 4K > > page), iter->level is 1 (PG_LEVEL_4K), and in case of 5 level paging, > > the iter->level is mmu->shadow_root_level, which is 5. However, struct > > kvm_mmu_page's level currently is not set correctly when it is allocated > > in kvm_tdp_mmu_map(). When iterator hits non-present SPTE and needs to > > allocate a new child page table, currently iter->level, which is the > > level of the page table where the non-present SPTE belongs to, is used. > > This results in struct kvm_mmu_page's level always having its parent's > > level (excpet root table's level, which is initialized explicitly using > > mmu->shadow_root_level). This is kinda wrong, and not consistent with > > existing non TDP MMU code. Fortuantely the sp->role.level is only used > > in handle_removed_tdp_mmu_page(), which apparently is already aware of > > this, and handles correctly. However to make it consistent with non TDP > > MMU code (and fix the issue that both root page table and any child of > > it having shadow_root_level), fix this by using iter->level - 1 in > > kvm_tdp_mmu_map(). Also modify handle_removed_tdp_mmu_page() to handle > > such change. > > Ugh. Thank you for catching this. This is going to take me a bit to > review as I should audit the code more broadly for this problem in the > TDP MMU. > It would probably also be a good idea to add a comment on the level > field to say that it represents the level of the SPTEs in the > associated page, not the level of the SPTE that links to the > associated page. > Hopefully that will prevent similar future misunderstandings. Regarding to adding a comment, sorry I had a hard time to figure out where to add. Did you mean level field of 'struct kvm_mmu_page_role', or 'struct tdp_iter'? If it is the former, to me not quite useful. I ended up with below. Is it OK to you? If you still think a comment of level should be added, would you be more specific so that I can add it? ------------------------------------------------------------------------ TDP MMU iterator's level is identical to page table's actual level. For instance, for the last level page table (whose entry points to one 4K page), iter->level is 1 (PG_LEVEL_4K), and in case of 5 level paging, the iter->level is mmu->shadow_root_level, which is 5. However, struct kvm_mmu_page's level currently is not set correctly when it is allocated in kvm_tdp_mmu_map(). When iterator hits non-present SPTE and needs to allocate a new child page table, currently iter->level, which is the level of the page table where the non-present SPTE belongs to, is used. This results in struct kvm_mmu_page's level always having its parent's level (excpet root table's level, which is initialized explicitly using mmu->shadow_root_level). This is kinda wrong, and not consistent with existing non TDP MMU code. Fortuantely sp->role.level is only used in handle_removed_tdp_mmu_page() and kvm_tdp_mmu_zap_sp(), and they are already aware of this and behave correctly. However to make it consistent with legacy MMU code (and fix the issue that both root page table and its child page table have shadow_root_level), use iter->level - 1 in kvm_tdp_mmu_map(), and change handle_removed_tdp_mmu_page() and kvm_tdp_mmu_zap_sp() accordingly. Signed-off-by: Kai Huang <kai.huang@intel.com> --- arch/x86/kvm/mmu/tdp_mmu.c | 8 ++++---- arch/x86/kvm/mmu/tdp_mmu.h | 2 +- 2 files changed, 5 insertions(+), 5 deletions(-) diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 5e28fbabcd35..45fb889f6a94 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -335,7 +335,7 @@ static void handle_removed_tdp_mmu_page(struct kvm *kvm, tdp_ptep_t pt, for (i = 0; i < PT64_ENT_PER_PAGE; i++) { sptep = rcu_dereference(pt) + i; - gfn = base_gfn + (i * KVM_PAGES_PER_HPAGE(level - 1)); + gfn = base_gfn + i * KVM_PAGES_PER_HPAGE(level); if (shared) { /* @@ -377,12 +377,12 @@ static void handle_removed_tdp_mmu_page(struct kvm *kvm, tdp_ptep_t pt, WRITE_ONCE(*sptep, REMOVED_SPTE); } handle_changed_spte(kvm, kvm_mmu_page_as_id(sp), gfn, - old_child_spte, REMOVED_SPTE, level - 1, + old_child_spte, REMOVED_SPTE, level, shared); } kvm_flush_remote_tlbs_with_address(kvm, gfn, - KVM_PAGES_PER_HPAGE(level)); + KVM_PAGES_PER_HPAGE(level + 1)); call_rcu(&sp->rcu_head, tdp_mmu_free_sp_rcu_callback); } @@ -1013,7 +1013,7 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, } if (!is_shadow_present_pte(iter.old_spte)) { - sp = alloc_tdp_mmu_page(vcpu, iter.gfn, iter.level); + sp = alloc_tdp_mmu_page(vcpu, iter.gfn, iter.level - 1); child_pt = sp->spt; new_spte = make_nonleaf_spte(child_pt, diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h index 5fdf63090451..7f9974c5d0b4 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.h +++ b/arch/x86/kvm/mmu/tdp_mmu.h @@ -31,7 +31,7 @@ static inline bool kvm_tdp_mmu_zap_gfn_range(struct kvm *kvm, int as_id, } static inline bool kvm_tdp_mmu_zap_sp(struct kvm *kvm, struct kvm_mmu_page *sp) { - gfn_t end = sp->gfn + KVM_PAGES_PER_HPAGE(sp->role.level); + gfn_t end = sp->gfn + KVM_PAGES_PER_HPAGE(sp->role.level + 1); /* * Don't allow yielding, as the caller may have a flush pending. Note,
On Thu, May 6, 2021 at 1:00 AM Kai Huang <kai.huang@intel.com> wrote: > > On Wed, 2021-05-05 at 09:28 -0700, Ben Gardon wrote: > > On Wed, May 5, 2021 at 2:38 AM Kai Huang <kai.huang@intel.com> wrote: > > > > > > TDP MMU iterator's level is identical to page table's actual level. For > > > instance, for the last level page table (whose entry points to one 4K > > > page), iter->level is 1 (PG_LEVEL_4K), and in case of 5 level paging, > > > the iter->level is mmu->shadow_root_level, which is 5. However, struct > > > kvm_mmu_page's level currently is not set correctly when it is allocated > > > in kvm_tdp_mmu_map(). When iterator hits non-present SPTE and needs to > > > allocate a new child page table, currently iter->level, which is the > > > level of the page table where the non-present SPTE belongs to, is used. > > > This results in struct kvm_mmu_page's level always having its parent's > > > level (excpet root table's level, which is initialized explicitly using > > > mmu->shadow_root_level). This is kinda wrong, and not consistent with > > > existing non TDP MMU code. Fortuantely the sp->role.level is only used > > > in handle_removed_tdp_mmu_page(), which apparently is already aware of > > > this, and handles correctly. However to make it consistent with non TDP > > > MMU code (and fix the issue that both root page table and any child of > > > it having shadow_root_level), fix this by using iter->level - 1 in > > > kvm_tdp_mmu_map(). Also modify handle_removed_tdp_mmu_page() to handle > > > such change. > > > > Ugh. Thank you for catching this. This is going to take me a bit to > > review as I should audit the code more broadly for this problem in the > > TDP MMU. > > It would probably also be a good idea to add a comment on the level > > field to say that it represents the level of the SPTEs in the > > associated page, not the level of the SPTE that links to the > > associated page. > > Hopefully that will prevent similar future misunderstandings. > > Regarding to adding a comment, sorry I had a hard time to figure out where to add. Did > you mean level field of 'struct kvm_mmu_page_role', or 'struct tdp_iter'? If it is the > former, to me not quite useful. I meant the level field of 'struct kvm_mmu_page_role', but if you don't think it makes sense to add one there, I don't feel strongly either way. > > I ended up with below. Is it OK to you? Yeah, it looks good to me. > > If you still think a comment of level should be added, would you be more specific so that > I can add it? struct { + /* + * The level of the SPT tracked by this SP, as opposed to the level of the + * parent SPTE linking this SPT. + */ unsigned level:4; ... I guess that does sound kind of unnecessary. > > ------------------------------------------------------------------------ > > TDP MMU iterator's level is identical to page table's actual level. For > instance, for the last level page table (whose entry points to one 4K > page), iter->level is 1 (PG_LEVEL_4K), and in case of 5 level paging, > the iter->level is mmu->shadow_root_level, which is 5. However, struct > kvm_mmu_page's level currently is not set correctly when it is allocated > in kvm_tdp_mmu_map(). When iterator hits non-present SPTE and needs to > allocate a new child page table, currently iter->level, which is the > level of the page table where the non-present SPTE belongs to, is used. > This results in struct kvm_mmu_page's level always having its parent's > level (excpet root table's level, which is initialized explicitly using > mmu->shadow_root_level). > > This is kinda wrong, and not consistent with existing non TDP MMU code. > Fortuantely sp->role.level is only used in handle_removed_tdp_mmu_page() > and kvm_tdp_mmu_zap_sp(), and they are already aware of this and behave > correctly. However to make it consistent with legacy MMU code (and fix > the issue that both root page table and its child page table have > shadow_root_level), use iter->level - 1 in kvm_tdp_mmu_map(), and change > handle_removed_tdp_mmu_page() and kvm_tdp_mmu_zap_sp() accordingly. > > Signed-off-by: Kai Huang <kai.huang@intel.com> > --- > arch/x86/kvm/mmu/tdp_mmu.c | 8 ++++---- > arch/x86/kvm/mmu/tdp_mmu.h | 2 +- > 2 files changed, 5 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c > index 5e28fbabcd35..45fb889f6a94 100644 > --- a/arch/x86/kvm/mmu/tdp_mmu.c > +++ b/arch/x86/kvm/mmu/tdp_mmu.c > @@ -335,7 +335,7 @@ static void handle_removed_tdp_mmu_page(struct kvm *kvm, tdp_ptep_t > pt, > > for (i = 0; i < PT64_ENT_PER_PAGE; i++) { > sptep = rcu_dereference(pt) + i; > - gfn = base_gfn + (i * KVM_PAGES_PER_HPAGE(level - 1)); > + gfn = base_gfn + i * KVM_PAGES_PER_HPAGE(level); > > if (shared) { > /* > @@ -377,12 +377,12 @@ static void handle_removed_tdp_mmu_page(struct kvm *kvm, tdp_ptep_t > pt, > WRITE_ONCE(*sptep, REMOVED_SPTE); > } > handle_changed_spte(kvm, kvm_mmu_page_as_id(sp), gfn, > - old_child_spte, REMOVED_SPTE, level - 1, > + old_child_spte, REMOVED_SPTE, level, > shared); > } > > kvm_flush_remote_tlbs_with_address(kvm, gfn, > - KVM_PAGES_PER_HPAGE(level)); > + KVM_PAGES_PER_HPAGE(level + 1)); > > call_rcu(&sp->rcu_head, tdp_mmu_free_sp_rcu_callback); > } > @@ -1013,7 +1013,7 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 > error_code, > } > > if (!is_shadow_present_pte(iter.old_spte)) { > - sp = alloc_tdp_mmu_page(vcpu, iter.gfn, iter.level); > + sp = alloc_tdp_mmu_page(vcpu, iter.gfn, iter.level - 1); > child_pt = sp->spt; > > new_spte = make_nonleaf_spte(child_pt, > diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h > index 5fdf63090451..7f9974c5d0b4 100644 > --- a/arch/x86/kvm/mmu/tdp_mmu.h > +++ b/arch/x86/kvm/mmu/tdp_mmu.h > @@ -31,7 +31,7 @@ static inline bool kvm_tdp_mmu_zap_gfn_range(struct kvm *kvm, int as_id, > } > static inline bool kvm_tdp_mmu_zap_sp(struct kvm *kvm, struct kvm_mmu_page *sp) > { > - gfn_t end = sp->gfn + KVM_PAGES_PER_HPAGE(sp->role.level); > + gfn_t end = sp->gfn + KVM_PAGES_PER_HPAGE(sp->role.level + 1); > > /* > * Don't allow yielding, as the caller may have a flush pending. Note, > -- > 2.31.1 > > > > > > > > > > Signed-off-by: Kai Huang <kai.huang@intel.com> > > > --- > > > arch/x86/kvm/mmu/tdp_mmu.c | 8 ++++---- > > > 1 file changed, 4 insertions(+), 4 deletions(-) > > > > > > diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c > > > index debe8c3ec844..bcfb87e1c06e 100644 > > > --- a/arch/x86/kvm/mmu/tdp_mmu.c > > > +++ b/arch/x86/kvm/mmu/tdp_mmu.c > > > @@ -335,7 +335,7 @@ static void handle_removed_tdp_mmu_page(struct kvm *kvm, tdp_ptep_t pt, > > > > > > for (i = 0; i < PT64_ENT_PER_PAGE; i++) { > > > sptep = rcu_dereference(pt) + i; > > > - gfn = base_gfn + (i * KVM_PAGES_PER_HPAGE(level - 1)); > > > + gfn = base_gfn + i * KVM_PAGES_PER_HPAGE(level); > > > > > > if (shared) { > > > /* > > > @@ -377,12 +377,12 @@ static void handle_removed_tdp_mmu_page(struct kvm *kvm, tdp_ptep_t pt, > > > WRITE_ONCE(*sptep, REMOVED_SPTE); > > > } > > > handle_changed_spte(kvm, kvm_mmu_page_as_id(sp), gfn, > > > - old_child_spte, REMOVED_SPTE, level - 1, > > > + old_child_spte, REMOVED_SPTE, level, > > > shared); > > > } > > > > > > kvm_flush_remote_tlbs_with_address(kvm, gfn, > > > - KVM_PAGES_PER_HPAGE(level)); > > > + KVM_PAGES_PER_HPAGE(level + 1)); > > > > > > call_rcu(&sp->rcu_head, tdp_mmu_free_sp_rcu_callback); > > > } > > > @@ -1009,7 +1009,7 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, > > > } > > > > > > if (!is_shadow_present_pte(iter.old_spte)) { > > > - sp = alloc_tdp_mmu_page(vcpu, iter.gfn, iter.level); > > > + sp = alloc_tdp_mmu_page(vcpu, iter.gfn, iter.level - 1); > > > child_pt = sp->spt; > > > > > > new_spte = make_nonleaf_spte(child_pt, > > > -- > > > 2.31.1 > > > > >
On Thu, May 6, 2021 at 9:22 AM Ben Gardon <bgardon@google.com> wrote: > > On Thu, May 6, 2021 at 1:00 AM Kai Huang <kai.huang@intel.com> wrote: > > > > On Wed, 2021-05-05 at 09:28 -0700, Ben Gardon wrote: > > > On Wed, May 5, 2021 at 2:38 AM Kai Huang <kai.huang@intel.com> wrote: > > > > > > > > TDP MMU iterator's level is identical to page table's actual level. For > > > > instance, for the last level page table (whose entry points to one 4K > > > > page), iter->level is 1 (PG_LEVEL_4K), and in case of 5 level paging, > > > > the iter->level is mmu->shadow_root_level, which is 5. However, struct > > > > kvm_mmu_page's level currently is not set correctly when it is allocated > > > > in kvm_tdp_mmu_map(). When iterator hits non-present SPTE and needs to > > > > allocate a new child page table, currently iter->level, which is the > > > > level of the page table where the non-present SPTE belongs to, is used. > > > > This results in struct kvm_mmu_page's level always having its parent's > > > > level (excpet root table's level, which is initialized explicitly using > > > > mmu->shadow_root_level). This is kinda wrong, and not consistent with > > > > existing non TDP MMU code. Fortuantely the sp->role.level is only used > > > > in handle_removed_tdp_mmu_page(), which apparently is already aware of > > > > this, and handles correctly. However to make it consistent with non TDP > > > > MMU code (and fix the issue that both root page table and any child of > > > > it having shadow_root_level), fix this by using iter->level - 1 in > > > > kvm_tdp_mmu_map(). Also modify handle_removed_tdp_mmu_page() to handle > > > > such change. > > > > > > Ugh. Thank you for catching this. This is going to take me a bit to > > > review as I should audit the code more broadly for this problem in the > > > TDP MMU. > > > It would probably also be a good idea to add a comment on the level > > > field to say that it represents the level of the SPTEs in the > > > associated page, not the level of the SPTE that links to the > > > associated page. > > > Hopefully that will prevent similar future misunderstandings. > > > > Regarding to adding a comment, sorry I had a hard time to figure out where to add. Did > > you mean level field of 'struct kvm_mmu_page_role', or 'struct tdp_iter'? If it is the > > former, to me not quite useful. > > I meant the level field of 'struct kvm_mmu_page_role', but if you > don't think it makes sense to add one there, I don't feel strongly > either way. > > > > > I ended up with below. Is it OK to you? > > Yeah, it looks good to me. > > > > > If you still think a comment of level should be added, would you be more specific so that > > I can add it? > > struct { > + /* > + * The level of the SPT tracked by this SP, as opposed to the > level of the > + * parent SPTE linking this SPT. > + */ > unsigned level:4; > > ... I guess that does sound kind of unnecessary. > > > > > ------------------------------------------------------------------------ > > > > TDP MMU iterator's level is identical to page table's actual level. For > > instance, for the last level page table (whose entry points to one 4K > > page), iter->level is 1 (PG_LEVEL_4K), and in case of 5 level paging, > > the iter->level is mmu->shadow_root_level, which is 5. However, struct > > kvm_mmu_page's level currently is not set correctly when it is allocated > > in kvm_tdp_mmu_map(). When iterator hits non-present SPTE and needs to > > allocate a new child page table, currently iter->level, which is the > > level of the page table where the non-present SPTE belongs to, is used. > > This results in struct kvm_mmu_page's level always having its parent's > > level (excpet root table's level, which is initialized explicitly using > > mmu->shadow_root_level). > > > > This is kinda wrong, and not consistent with existing non TDP MMU code. > > Fortuantely sp->role.level is only used in handle_removed_tdp_mmu_page() > > and kvm_tdp_mmu_zap_sp(), and they are already aware of this and behave > > correctly. However to make it consistent with legacy MMU code (and fix > > the issue that both root page table and its child page table have > > shadow_root_level), use iter->level - 1 in kvm_tdp_mmu_map(), and change > > handle_removed_tdp_mmu_page() and kvm_tdp_mmu_zap_sp() accordingly. > > > > Signed-off-by: Kai Huang <kai.huang@intel.com> Ooops, I meant to add: Reviewed-by: Ben Gardon <bgardon@google.com> > > --- > > arch/x86/kvm/mmu/tdp_mmu.c | 8 ++++---- > > arch/x86/kvm/mmu/tdp_mmu.h | 2 +- > > 2 files changed, 5 insertions(+), 5 deletions(-) > > > > diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c > > index 5e28fbabcd35..45fb889f6a94 100644 > > --- a/arch/x86/kvm/mmu/tdp_mmu.c > > +++ b/arch/x86/kvm/mmu/tdp_mmu.c > > @@ -335,7 +335,7 @@ static void handle_removed_tdp_mmu_page(struct kvm *kvm, tdp_ptep_t > > pt, > > > > for (i = 0; i < PT64_ENT_PER_PAGE; i++) { > > sptep = rcu_dereference(pt) + i; > > - gfn = base_gfn + (i * KVM_PAGES_PER_HPAGE(level - 1)); > > + gfn = base_gfn + i * KVM_PAGES_PER_HPAGE(level); > > > > if (shared) { > > /* > > @@ -377,12 +377,12 @@ static void handle_removed_tdp_mmu_page(struct kvm *kvm, tdp_ptep_t > > pt, > > WRITE_ONCE(*sptep, REMOVED_SPTE); > > } > > handle_changed_spte(kvm, kvm_mmu_page_as_id(sp), gfn, > > - old_child_spte, REMOVED_SPTE, level - 1, > > + old_child_spte, REMOVED_SPTE, level, > > shared); > > } > > > > kvm_flush_remote_tlbs_with_address(kvm, gfn, > > - KVM_PAGES_PER_HPAGE(level)); > > + KVM_PAGES_PER_HPAGE(level + 1)); > > > > call_rcu(&sp->rcu_head, tdp_mmu_free_sp_rcu_callback); > > } > > @@ -1013,7 +1013,7 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 > > error_code, > > } > > > > if (!is_shadow_present_pte(iter.old_spte)) { > > - sp = alloc_tdp_mmu_page(vcpu, iter.gfn, iter.level); > > + sp = alloc_tdp_mmu_page(vcpu, iter.gfn, iter.level - 1); > > child_pt = sp->spt; > > > > new_spte = make_nonleaf_spte(child_pt, > > diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h > > index 5fdf63090451..7f9974c5d0b4 100644 > > --- a/arch/x86/kvm/mmu/tdp_mmu.h > > +++ b/arch/x86/kvm/mmu/tdp_mmu.h > > @@ -31,7 +31,7 @@ static inline bool kvm_tdp_mmu_zap_gfn_range(struct kvm *kvm, int as_id, > > } > > static inline bool kvm_tdp_mmu_zap_sp(struct kvm *kvm, struct kvm_mmu_page *sp) > > { > > - gfn_t end = sp->gfn + KVM_PAGES_PER_HPAGE(sp->role.level); > > + gfn_t end = sp->gfn + KVM_PAGES_PER_HPAGE(sp->role.level + 1); > > > > /* > > * Don't allow yielding, as the caller may have a flush pending. Note, > > -- > > 2.31.1 > > > > > > > > > > > > > > > Signed-off-by: Kai Huang <kai.huang@intel.com> > > > > --- > > > > arch/x86/kvm/mmu/tdp_mmu.c | 8 ++++---- > > > > 1 file changed, 4 insertions(+), 4 deletions(-) > > > > > > > > diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c > > > > index debe8c3ec844..bcfb87e1c06e 100644 > > > > --- a/arch/x86/kvm/mmu/tdp_mmu.c > > > > +++ b/arch/x86/kvm/mmu/tdp_mmu.c > > > > @@ -335,7 +335,7 @@ static void handle_removed_tdp_mmu_page(struct kvm *kvm, tdp_ptep_t pt, > > > > > > > > for (i = 0; i < PT64_ENT_PER_PAGE; i++) { > > > > sptep = rcu_dereference(pt) + i; > > > > - gfn = base_gfn + (i * KVM_PAGES_PER_HPAGE(level - 1)); > > > > + gfn = base_gfn + i * KVM_PAGES_PER_HPAGE(level); > > > > > > > > if (shared) { > > > > /* > > > > @@ -377,12 +377,12 @@ static void handle_removed_tdp_mmu_page(struct kvm *kvm, tdp_ptep_t pt, > > > > WRITE_ONCE(*sptep, REMOVED_SPTE); > > > > } > > > > handle_changed_spte(kvm, kvm_mmu_page_as_id(sp), gfn, > > > > - old_child_spte, REMOVED_SPTE, level - 1, > > > > + old_child_spte, REMOVED_SPTE, level, > > > > shared); > > > > } > > > > > > > > kvm_flush_remote_tlbs_with_address(kvm, gfn, > > > > - KVM_PAGES_PER_HPAGE(level)); > > > > + KVM_PAGES_PER_HPAGE(level + 1)); > > > > > > > > call_rcu(&sp->rcu_head, tdp_mmu_free_sp_rcu_callback); > > > > } > > > > @@ -1009,7 +1009,7 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, > > > > } > > > > > > > > if (!is_shadow_present_pte(iter.old_spte)) { > > > > - sp = alloc_tdp_mmu_page(vcpu, iter.gfn, iter.level); > > > > + sp = alloc_tdp_mmu_page(vcpu, iter.gfn, iter.level - 1); > > > > child_pt = sp->spt; > > > > > > > > new_spte = make_nonleaf_spte(child_pt, > > > > -- > > > > 2.31.1 > > > > > > > >
On Thu, 2021-05-06 at 09:23 -0700, Ben Gardon wrote: > On Thu, May 6, 2021 at 9:22 AM Ben Gardon <bgardon@google.com> wrote: > > > > On Thu, May 6, 2021 at 1:00 AM Kai Huang <kai.huang@intel.com> wrote: > > > > > > On Wed, 2021-05-05 at 09:28 -0700, Ben Gardon wrote: > > > > On Wed, May 5, 2021 at 2:38 AM Kai Huang <kai.huang@intel.com> wrote: > > > > > > > > > > TDP MMU iterator's level is identical to page table's actual level. For > > > > > instance, for the last level page table (whose entry points to one 4K > > > > > page), iter->level is 1 (PG_LEVEL_4K), and in case of 5 level paging, > > > > > the iter->level is mmu->shadow_root_level, which is 5. However, struct > > > > > kvm_mmu_page's level currently is not set correctly when it is allocated > > > > > in kvm_tdp_mmu_map(). When iterator hits non-present SPTE and needs to > > > > > allocate a new child page table, currently iter->level, which is the > > > > > level of the page table where the non-present SPTE belongs to, is used. > > > > > This results in struct kvm_mmu_page's level always having its parent's > > > > > level (excpet root table's level, which is initialized explicitly using > > > > > mmu->shadow_root_level). This is kinda wrong, and not consistent with > > > > > existing non TDP MMU code. Fortuantely the sp->role.level is only used > > > > > in handle_removed_tdp_mmu_page(), which apparently is already aware of > > > > > this, and handles correctly. However to make it consistent with non TDP > > > > > MMU code (and fix the issue that both root page table and any child of > > > > > it having shadow_root_level), fix this by using iter->level - 1 in > > > > > kvm_tdp_mmu_map(). Also modify handle_removed_tdp_mmu_page() to handle > > > > > such change. > > > > > > > > Ugh. Thank you for catching this. This is going to take me a bit to > > > > review as I should audit the code more broadly for this problem in the > > > > TDP MMU. > > > > It would probably also be a good idea to add a comment on the level > > > > field to say that it represents the level of the SPTEs in the > > > > associated page, not the level of the SPTE that links to the > > > > associated page. > > > > Hopefully that will prevent similar future misunderstandings. > > > > > > Regarding to adding a comment, sorry I had a hard time to figure out where to add. Did > > > you mean level field of 'struct kvm_mmu_page_role', or 'struct tdp_iter'? If it is the > > > former, to me not quite useful. > > > > I meant the level field of 'struct kvm_mmu_page_role', but if you > > don't think it makes sense to add one there, I don't feel strongly > > either way. > > > > > > > > I ended up with below. Is it OK to you? > > > > Yeah, it looks good to me. > > > > > > > > If you still think a comment of level should be added, would you be more specific so that > > > I can add it? > > > > struct { > > + /* > > + * The level of the SPT tracked by this SP, as opposed to the > > level of the > > + * parent SPTE linking this SPT. > > + */ > > unsigned level:4; > > > > ... I guess that does sound kind of unnecessary. Thanks for explanation. It looks a little bit unnecessary for me. And if necessary, perhaps a separate patch :) > > > > > > > > ------------------------------------------------------------------------ > > > > > > TDP MMU iterator's level is identical to page table's actual level. For > > > instance, for the last level page table (whose entry points to one 4K > > > page), iter->level is 1 (PG_LEVEL_4K), and in case of 5 level paging, > > > the iter->level is mmu->shadow_root_level, which is 5. However, struct > > > kvm_mmu_page's level currently is not set correctly when it is allocated > > > in kvm_tdp_mmu_map(). When iterator hits non-present SPTE and needs to > > > allocate a new child page table, currently iter->level, which is the > > > level of the page table where the non-present SPTE belongs to, is used. > > > This results in struct kvm_mmu_page's level always having its parent's > > > level (excpet root table's level, which is initialized explicitly using > > > mmu->shadow_root_level). > > > > > > This is kinda wrong, and not consistent with existing non TDP MMU code. > > > Fortuantely sp->role.level is only used in handle_removed_tdp_mmu_page() > > > and kvm_tdp_mmu_zap_sp(), and they are already aware of this and behave > > > correctly. However to make it consistent with legacy MMU code (and fix > > > the issue that both root page table and its child page table have > > > shadow_root_level), use iter->level - 1 in kvm_tdp_mmu_map(), and change > > > handle_removed_tdp_mmu_page() and kvm_tdp_mmu_zap_sp() accordingly. > > > > > > Signed-off-by: Kai Huang <kai.huang@intel.com> > > Ooops, I meant to add: > > Reviewed-by: Ben Gardon <bgardon@google.com> Thank you! > > > > --- > > > arch/x86/kvm/mmu/tdp_mmu.c | 8 ++++---- > > > arch/x86/kvm/mmu/tdp_mmu.h | 2 +- > > > 2 files changed, 5 insertions(+), 5 deletions(-) > > > > > > diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c > > > index 5e28fbabcd35..45fb889f6a94 100644 > > > --- a/arch/x86/kvm/mmu/tdp_mmu.c > > > +++ b/arch/x86/kvm/mmu/tdp_mmu.c > > > @@ -335,7 +335,7 @@ static void handle_removed_tdp_mmu_page(struct kvm *kvm, tdp_ptep_t > > > pt, > > > > > > for (i = 0; i < PT64_ENT_PER_PAGE; i++) { > > > sptep = rcu_dereference(pt) + i; > > > - gfn = base_gfn + (i * KVM_PAGES_PER_HPAGE(level - 1)); > > > + gfn = base_gfn + i * KVM_PAGES_PER_HPAGE(level); > > > > > > if (shared) { > > > /* > > > @@ -377,12 +377,12 @@ static void handle_removed_tdp_mmu_page(struct kvm *kvm, tdp_ptep_t > > > pt, > > > WRITE_ONCE(*sptep, REMOVED_SPTE); > > > } > > > handle_changed_spte(kvm, kvm_mmu_page_as_id(sp), gfn, > > > - old_child_spte, REMOVED_SPTE, level - 1, > > > + old_child_spte, REMOVED_SPTE, level, > > > shared); > > > } > > > > > > kvm_flush_remote_tlbs_with_address(kvm, gfn, > > > - KVM_PAGES_PER_HPAGE(level)); > > > + KVM_PAGES_PER_HPAGE(level + 1)); > > > > > > call_rcu(&sp->rcu_head, tdp_mmu_free_sp_rcu_callback); > > > } > > > @@ -1013,7 +1013,7 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 > > > error_code, > > > } > > > > > > if (!is_shadow_present_pte(iter.old_spte)) { > > > - sp = alloc_tdp_mmu_page(vcpu, iter.gfn, iter.level); > > > + sp = alloc_tdp_mmu_page(vcpu, iter.gfn, iter.level - 1); > > > child_pt = sp->spt; > > > > > > new_spte = make_nonleaf_spte(child_pt, > > > diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h > > > index 5fdf63090451..7f9974c5d0b4 100644 > > > --- a/arch/x86/kvm/mmu/tdp_mmu.h > > > +++ b/arch/x86/kvm/mmu/tdp_mmu.h > > > @@ -31,7 +31,7 @@ static inline bool kvm_tdp_mmu_zap_gfn_range(struct kvm *kvm, int as_id, > > > } > > > static inline bool kvm_tdp_mmu_zap_sp(struct kvm *kvm, struct kvm_mmu_page *sp) > > > { > > > - gfn_t end = sp->gfn + KVM_PAGES_PER_HPAGE(sp->role.level); > > > + gfn_t end = sp->gfn + KVM_PAGES_PER_HPAGE(sp->role.level + 1); > > > > > > /* > > > * Don't allow yielding, as the caller may have a flush pending. Note, > > > -- > > > 2.31.1 > > > > > > > > > > > > > > > > > > > > Signed-off-by: Kai Huang <kai.huang@intel.com> > > > > > --- > > > > > arch/x86/kvm/mmu/tdp_mmu.c | 8 ++++---- > > > > > 1 file changed, 4 insertions(+), 4 deletions(-) > > > > > > > > > > diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c > > > > > index debe8c3ec844..bcfb87e1c06e 100644 > > > > > --- a/arch/x86/kvm/mmu/tdp_mmu.c > > > > > +++ b/arch/x86/kvm/mmu/tdp_mmu.c > > > > > @@ -335,7 +335,7 @@ static void handle_removed_tdp_mmu_page(struct kvm *kvm, tdp_ptep_t pt, > > > > > > > > > > for (i = 0; i < PT64_ENT_PER_PAGE; i++) { > > > > > sptep = rcu_dereference(pt) + i; > > > > > - gfn = base_gfn + (i * KVM_PAGES_PER_HPAGE(level - 1)); > > > > > + gfn = base_gfn + i * KVM_PAGES_PER_HPAGE(level); > > > > > > > > > > if (shared) { > > > > > /* > > > > > @@ -377,12 +377,12 @@ static void handle_removed_tdp_mmu_page(struct kvm *kvm, tdp_ptep_t pt, > > > > > WRITE_ONCE(*sptep, REMOVED_SPTE); > > > > > } > > > > > handle_changed_spte(kvm, kvm_mmu_page_as_id(sp), gfn, > > > > > - old_child_spte, REMOVED_SPTE, level - 1, > > > > > + old_child_spte, REMOVED_SPTE, level, > > > > > shared); > > > > > } > > > > > > > > > > kvm_flush_remote_tlbs_with_address(kvm, gfn, > > > > > - KVM_PAGES_PER_HPAGE(level)); > > > > > + KVM_PAGES_PER_HPAGE(level + 1)); > > > > > > > > > > call_rcu(&sp->rcu_head, tdp_mmu_free_sp_rcu_callback); > > > > > } > > > > > @@ -1009,7 +1009,7 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, > > > > > } > > > > > > > > > > if (!is_shadow_present_pte(iter.old_spte)) { > > > > > - sp = alloc_tdp_mmu_page(vcpu, iter.gfn, iter.level); > > > > > + sp = alloc_tdp_mmu_page(vcpu, iter.gfn, iter.level - 1); > > > > > child_pt = sp->spt; > > > > > > > > > > new_spte = make_nonleaf_spte(child_pt, > > > > > -- > > > > > 2.31.1 > > > > > > > > > > >
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index debe8c3ec844..bcfb87e1c06e 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -335,7 +335,7 @@ static void handle_removed_tdp_mmu_page(struct kvm *kvm, tdp_ptep_t pt, for (i = 0; i < PT64_ENT_PER_PAGE; i++) { sptep = rcu_dereference(pt) + i; - gfn = base_gfn + (i * KVM_PAGES_PER_HPAGE(level - 1)); + gfn = base_gfn + i * KVM_PAGES_PER_HPAGE(level); if (shared) { /* @@ -377,12 +377,12 @@ static void handle_removed_tdp_mmu_page(struct kvm *kvm, tdp_ptep_t pt, WRITE_ONCE(*sptep, REMOVED_SPTE); } handle_changed_spte(kvm, kvm_mmu_page_as_id(sp), gfn, - old_child_spte, REMOVED_SPTE, level - 1, + old_child_spte, REMOVED_SPTE, level, shared); } kvm_flush_remote_tlbs_with_address(kvm, gfn, - KVM_PAGES_PER_HPAGE(level)); + KVM_PAGES_PER_HPAGE(level + 1)); call_rcu(&sp->rcu_head, tdp_mmu_free_sp_rcu_callback); } @@ -1009,7 +1009,7 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, } if (!is_shadow_present_pte(iter.old_spte)) { - sp = alloc_tdp_mmu_page(vcpu, iter.gfn, iter.level); + sp = alloc_tdp_mmu_page(vcpu, iter.gfn, iter.level - 1); child_pt = sp->spt; new_spte = make_nonleaf_spte(child_pt,
TDP MMU iterator's level is identical to page table's actual level. For instance, for the last level page table (whose entry points to one 4K page), iter->level is 1 (PG_LEVEL_4K), and in case of 5 level paging, the iter->level is mmu->shadow_root_level, which is 5. However, struct kvm_mmu_page's level currently is not set correctly when it is allocated in kvm_tdp_mmu_map(). When iterator hits non-present SPTE and needs to allocate a new child page table, currently iter->level, which is the level of the page table where the non-present SPTE belongs to, is used. This results in struct kvm_mmu_page's level always having its parent's level (excpet root table's level, which is initialized explicitly using mmu->shadow_root_level). This is kinda wrong, and not consistent with existing non TDP MMU code. Fortuantely the sp->role.level is only used in handle_removed_tdp_mmu_page(), which apparently is already aware of this, and handles correctly. However to make it consistent with non TDP MMU code (and fix the issue that both root page table and any child of it having shadow_root_level), fix this by using iter->level - 1 in kvm_tdp_mmu_map(). Also modify handle_removed_tdp_mmu_page() to handle such change. Signed-off-by: Kai Huang <kai.huang@intel.com> --- arch/x86/kvm/mmu/tdp_mmu.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)