| Message ID | 34246866043db7bab34a92fe22f359667ab155a0.1655761627.git.ashish.kalra@amd.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Add AMD Secure Nested Paging (SEV-SNP) | expand |
On Mon, Jun 20, 2022 at 4:12 PM Ashish Kalra <Ashish.Kalra@amd.com> wrote: > > From: Brijesh Singh <brijesh.singh@amd.com> > > When SEV-SNP is enabled in the guest VM, the guest memory pages can > either be a private or shared. A write from the hypervisor goes through > the RMP checks. If hardware sees that hypervisor is attempting to write > to a guest private page, then it triggers an RMP violation #PF. > > To avoid the RMP violation with GHCB pages, added new post_{map,unmap}_gfn > functions to verify if its safe to map GHCB pages. Uses a spinlock to > protect against the page state change for existing mapped pages. > > Need to add generic post_{map,unmap}_gfn() ops that can be used to verify > that its safe to map a given guest page in the hypervisor. > > This patch will need to be revisited later after consensus is reached on > how to manage guest private memory as probably UPM private memslots will > be able to handle this page state change more gracefully. > > Signed-off-by: Brijesh Singh <brijesh.singh@amd.com> > Signed-off by: Ashish Kalra <ashish.kalra@amd.com> > --- > arch/x86/include/asm/kvm-x86-ops.h | 1 + > arch/x86/include/asm/kvm_host.h | 3 ++ > arch/x86/kvm/svm/sev.c | 48 ++++++++++++++++++++++++++++-- > arch/x86/kvm/svm/svm.c | 3 ++ > arch/x86/kvm/svm/svm.h | 11 +++++++ > 5 files changed, 64 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h > index e0068e702692..2dd2bc0cf4c3 100644 > --- a/arch/x86/include/asm/kvm-x86-ops.h > +++ b/arch/x86/include/asm/kvm-x86-ops.h > @@ -130,6 +130,7 @@ KVM_X86_OP(vcpu_deliver_sipi_vector) > KVM_X86_OP_OPTIONAL_RET0(vcpu_get_apicv_inhibit_reasons); > KVM_X86_OP(alloc_apic_backing_page) > KVM_X86_OP_OPTIONAL(rmp_page_level_adjust) > +KVM_X86_OP(update_protected_guest_state) > > #undef KVM_X86_OP > #undef KVM_X86_OP_OPTIONAL > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 49b217dc8d7e..8abc0e724f5c 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -1522,7 +1522,10 @@ struct kvm_x86_ops { > unsigned long (*vcpu_get_apicv_inhibit_reasons)(struct kvm_vcpu *vcpu); > > void *(*alloc_apic_backing_page)(struct kvm_vcpu *vcpu); > + > void (*rmp_page_level_adjust)(struct kvm *kvm, kvm_pfn_t pfn, int *level); > + > + int (*update_protected_guest_state)(struct kvm_vcpu *vcpu); > }; > > struct kvm_x86_nested_ops { > diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c > index cb2d1bbb862b..4ed90331bca0 100644 > --- a/arch/x86/kvm/svm/sev.c > +++ b/arch/x86/kvm/svm/sev.c > @@ -341,6 +341,7 @@ static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp) > if (ret) > goto e_free; > > + spin_lock_init(&sev->psc_lock); > ret = sev_snp_init(&argp->error); > } else { > ret = sev_platform_init(&argp->error); > @@ -2828,19 +2829,28 @@ static inline int svm_map_ghcb(struct vcpu_svm *svm, struct kvm_host_map *map) > { > struct vmcb_control_area *control = &svm->vmcb->control; > u64 gfn = gpa_to_gfn(control->ghcb_gpa); > + struct kvm_vcpu *vcpu = &svm->vcpu; > > - if (kvm_vcpu_map(&svm->vcpu, gfn, map)) { > + if (kvm_vcpu_map(vcpu, gfn, map)) { > /* Unable to map GHCB from guest */ > pr_err("error mapping GHCB GFN [%#llx] from guest\n", gfn); > return -EFAULT; > } > > + if (sev_post_map_gfn(vcpu->kvm, map->gfn, map->pfn)) { > + kvm_vcpu_unmap(vcpu, map, false); > + return -EBUSY; > + } > + > return 0; > } > > static inline void svm_unmap_ghcb(struct vcpu_svm *svm, struct kvm_host_map *map) > { > - kvm_vcpu_unmap(&svm->vcpu, map, true); > + struct kvm_vcpu *vcpu = &svm->vcpu; > + > + kvm_vcpu_unmap(vcpu, map, true); > + sev_post_unmap_gfn(vcpu->kvm, map->gfn, map->pfn); > } > > static void dump_ghcb(struct vcpu_svm *svm) > @@ -3383,6 +3393,8 @@ static int __snp_handle_page_state_change(struct kvm_vcpu *vcpu, enum psc_op op, > return PSC_UNDEF_ERR; > } > > + spin_lock(&sev->psc_lock); > + > write_lock(&kvm->mmu_lock); > > rc = kvm_mmu_get_tdp_walk(vcpu, gpa, &pfn, &npt_level); > @@ -3417,6 +3429,8 @@ static int __snp_handle_page_state_change(struct kvm_vcpu *vcpu, enum psc_op op, > > write_unlock(&kvm->mmu_lock); > > + spin_unlock(&sev->psc_lock); There is a corner case where the psc_lock is not released. If kvm_mmu_get_tdp_walk fails, the lock will be kept and will cause soft lockup. > + > if (rc) { > pr_err_ratelimited("Error op %d gpa %llx pfn %llx level %d rc %d\n", > op, gpa, pfn, level, rc); > @@ -3965,3 +3979,33 @@ void sev_rmp_page_level_adjust(struct kvm *kvm, kvm_pfn_t pfn, int *level) > /* Adjust the level to keep the NPT and RMP in sync */ > *level = min_t(size_t, *level, rmp_level); > } > + > +int sev_post_map_gfn(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn) > +{ > + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; > + int level; > + > + if (!sev_snp_guest(kvm)) > + return 0; > + > + spin_lock(&sev->psc_lock); > + > + /* If pfn is not added as private then fail */ > + if (snp_lookup_rmpentry(pfn, &level) == 1) { > + spin_unlock(&sev->psc_lock); > + pr_err_ratelimited("failed to map private gfn 0x%llx pfn 0x%llx\n", gfn, pfn); > + return -EBUSY; > + } > + > + return 0; > +} > + > +void sev_post_unmap_gfn(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn) > +{ > + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; > + > + if (!sev_snp_guest(kvm)) > + return; > + > + spin_unlock(&sev->psc_lock); > +} > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c > index b24e0171cbf2..1c8e035ba011 100644 > --- a/arch/x86/kvm/svm/svm.c > +++ b/arch/x86/kvm/svm/svm.c > @@ -4734,7 +4734,10 @@ static struct kvm_x86_ops svm_x86_ops __initdata = { > .vcpu_get_apicv_inhibit_reasons = avic_vcpu_get_apicv_inhibit_reasons, > > .alloc_apic_backing_page = svm_alloc_apic_backing_page, > + > .rmp_page_level_adjust = sev_rmp_page_level_adjust, > + > + .update_protected_guest_state = sev_snp_update_protected_guest_state, > }; > > /* > diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h > index 54ff56cb6125..3fd95193ed8d 100644 > --- a/arch/x86/kvm/svm/svm.h > +++ b/arch/x86/kvm/svm/svm.h > @@ -79,19 +79,25 @@ struct kvm_sev_info { > bool active; /* SEV enabled guest */ > bool es_active; /* SEV-ES enabled guest */ > bool snp_active; /* SEV-SNP enabled guest */ > + > unsigned int asid; /* ASID used for this guest */ > unsigned int handle; /* SEV firmware handle */ > int fd; /* SEV device fd */ > + > unsigned long pages_locked; /* Number of pages locked */ > struct list_head regions_list; /* List of registered regions */ > + > u64 ap_jump_table; /* SEV-ES AP Jump Table address */ > + > struct kvm *enc_context_owner; /* Owner of copied encryption context */ > struct list_head mirror_vms; /* List of VMs mirroring */ > struct list_head mirror_entry; /* Use as a list entry of mirrors */ > struct misc_cg *misc_cg; /* For misc cgroup accounting */ > atomic_t migration_in_progress; > + > u64 snp_init_flags; > void *snp_context; /* SNP guest context page */ > + spinlock_t psc_lock; > }; > > struct kvm_svm { > @@ -702,6 +708,11 @@ void sev_es_prepare_switch_to_guest(struct sev_es_save_area *hostsa); > void sev_es_unmap_ghcb(struct vcpu_svm *svm); > struct page *snp_safe_alloc_page(struct kvm_vcpu *vcpu); > void sev_rmp_page_level_adjust(struct kvm *kvm, kvm_pfn_t pfn, int *level); > +int sev_post_map_gfn(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn); > +void sev_post_unmap_gfn(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn); > +void handle_rmp_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code); > +void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu); > +int sev_snp_update_protected_guest_state(struct kvm_vcpu *vcpu); > > /* vmenter.S */ > > -- > 2.25.1 >
On Wed, Aug 17, 2022 at 9:47 PM Alper Gun <alpergun@google.com> wrote: > > On Mon, Jun 20, 2022 at 4:12 PM Ashish Kalra <Ashish.Kalra@amd.com> wrote: > > > > From: Brijesh Singh <brijesh.singh@amd.com> > > > > When SEV-SNP is enabled in the guest VM, the guest memory pages can > > either be a private or shared. A write from the hypervisor goes through > > the RMP checks. If hardware sees that hypervisor is attempting to write > > to a guest private page, then it triggers an RMP violation #PF. > > > > To avoid the RMP violation with GHCB pages, added new post_{map,unmap}_gfn > > functions to verify if its safe to map GHCB pages. Uses a spinlock to > > protect against the page state change for existing mapped pages. > > > > Need to add generic post_{map,unmap}_gfn() ops that can be used to verify > > that its safe to map a given guest page in the hypervisor. > > > > This patch will need to be revisited later after consensus is reached on > > how to manage guest private memory as probably UPM private memslots will > > be able to handle this page state change more gracefully. > > > > Signed-off-by: Brijesh Singh <brijesh.singh@amd.com> > > Signed-off by: Ashish Kalra <ashish.kalra@amd.com> > > --- > > arch/x86/include/asm/kvm-x86-ops.h | 1 + > > arch/x86/include/asm/kvm_host.h | 3 ++ > > arch/x86/kvm/svm/sev.c | 48 ++++++++++++++++++++++++++++-- > > arch/x86/kvm/svm/svm.c | 3 ++ > > arch/x86/kvm/svm/svm.h | 11 +++++++ > > 5 files changed, 64 insertions(+), 2 deletions(-) > > > > diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h > > index e0068e702692..2dd2bc0cf4c3 100644 > > --- a/arch/x86/include/asm/kvm-x86-ops.h > > +++ b/arch/x86/include/asm/kvm-x86-ops.h > > @@ -130,6 +130,7 @@ KVM_X86_OP(vcpu_deliver_sipi_vector) > > KVM_X86_OP_OPTIONAL_RET0(vcpu_get_apicv_inhibit_reasons); > > KVM_X86_OP(alloc_apic_backing_page) > > KVM_X86_OP_OPTIONAL(rmp_page_level_adjust) > > +KVM_X86_OP(update_protected_guest_state) > > > > #undef KVM_X86_OP > > #undef KVM_X86_OP_OPTIONAL > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > > index 49b217dc8d7e..8abc0e724f5c 100644 > > --- a/arch/x86/include/asm/kvm_host.h > > +++ b/arch/x86/include/asm/kvm_host.h > > @@ -1522,7 +1522,10 @@ struct kvm_x86_ops { > > unsigned long (*vcpu_get_apicv_inhibit_reasons)(struct kvm_vcpu *vcpu); > > > > void *(*alloc_apic_backing_page)(struct kvm_vcpu *vcpu); > > + > > void (*rmp_page_level_adjust)(struct kvm *kvm, kvm_pfn_t pfn, int *level); > > + > > + int (*update_protected_guest_state)(struct kvm_vcpu *vcpu); > > }; > > > > struct kvm_x86_nested_ops { > > diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c > > index cb2d1bbb862b..4ed90331bca0 100644 > > --- a/arch/x86/kvm/svm/sev.c > > +++ b/arch/x86/kvm/svm/sev.c > > @@ -341,6 +341,7 @@ static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp) > > if (ret) > > goto e_free; > > > > + spin_lock_init(&sev->psc_lock); > > ret = sev_snp_init(&argp->error); > > } else { > > ret = sev_platform_init(&argp->error); > > @@ -2828,19 +2829,28 @@ static inline int svm_map_ghcb(struct vcpu_svm *svm, struct kvm_host_map *map) > > { > > struct vmcb_control_area *control = &svm->vmcb->control; > > u64 gfn = gpa_to_gfn(control->ghcb_gpa); > > + struct kvm_vcpu *vcpu = &svm->vcpu; > > > > - if (kvm_vcpu_map(&svm->vcpu, gfn, map)) { > > + if (kvm_vcpu_map(vcpu, gfn, map)) { > > /* Unable to map GHCB from guest */ > > pr_err("error mapping GHCB GFN [%#llx] from guest\n", gfn); > > return -EFAULT; > > } > > > > + if (sev_post_map_gfn(vcpu->kvm, map->gfn, map->pfn)) { > > + kvm_vcpu_unmap(vcpu, map, false); > > + return -EBUSY; > > + } > > + > > return 0; > > } > > > > static inline void svm_unmap_ghcb(struct vcpu_svm *svm, struct kvm_host_map *map) > > { > > - kvm_vcpu_unmap(&svm->vcpu, map, true); > > + struct kvm_vcpu *vcpu = &svm->vcpu; > > + > > + kvm_vcpu_unmap(vcpu, map, true); > > + sev_post_unmap_gfn(vcpu->kvm, map->gfn, map->pfn); > > } > > > > static void dump_ghcb(struct vcpu_svm *svm) > > @@ -3383,6 +3393,8 @@ static int __snp_handle_page_state_change(struct kvm_vcpu *vcpu, enum psc_op op, > > return PSC_UNDEF_ERR; > > } > > > > + spin_lock(&sev->psc_lock); > > + > > write_lock(&kvm->mmu_lock); > > > > rc = kvm_mmu_get_tdp_walk(vcpu, gpa, &pfn, &npt_level); > > @@ -3417,6 +3429,8 @@ static int __snp_handle_page_state_change(struct kvm_vcpu *vcpu, enum psc_op op, > > > > write_unlock(&kvm->mmu_lock); > > > > + spin_unlock(&sev->psc_lock); > > There is a corner case where the psc_lock is not released. If > kvm_mmu_get_tdp_walk fails, the lock will be kept and will cause soft > lockup. > > > + > > if (rc) { > > pr_err_ratelimited("Error op %d gpa %llx pfn %llx level %d rc %d\n", > > op, gpa, pfn, level, rc); > > @@ -3965,3 +3979,33 @@ void sev_rmp_page_level_adjust(struct kvm *kvm, kvm_pfn_t pfn, int *level) > > /* Adjust the level to keep the NPT and RMP in sync */ > > *level = min_t(size_t, *level, rmp_level); > > } > > + > > +int sev_post_map_gfn(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn) > > +{ > > + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; > > + int level; > > + > > + if (!sev_snp_guest(kvm)) > > + return 0; > > + > > + spin_lock(&sev->psc_lock); > > + > > + /* If pfn is not added as private then fail */ > > + if (snp_lookup_rmpentry(pfn, &level) == 1) { > > + spin_unlock(&sev->psc_lock); > > + pr_err_ratelimited("failed to map private gfn 0x%llx pfn 0x%llx\n", gfn, pfn); > > + return -EBUSY; > > + } > > + > > + return 0; > > +} > > + > > +void sev_post_unmap_gfn(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn) > > +{ > > + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; > > + > > + if (!sev_snp_guest(kvm)) > > + return; > > + > > + spin_unlock(&sev->psc_lock); > > +} > > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c > > index b24e0171cbf2..1c8e035ba011 100644 > > --- a/arch/x86/kvm/svm/svm.c > > +++ b/arch/x86/kvm/svm/svm.c > > @@ -4734,7 +4734,10 @@ static struct kvm_x86_ops svm_x86_ops __initdata = { > > .vcpu_get_apicv_inhibit_reasons = avic_vcpu_get_apicv_inhibit_reasons, > > > > .alloc_apic_backing_page = svm_alloc_apic_backing_page, > > + > > .rmp_page_level_adjust = sev_rmp_page_level_adjust, > > + > > + .update_protected_guest_state = sev_snp_update_protected_guest_state, > > }; I don't see this function sev_snp_update_protected_guest_state() being defined anywhere in this series. Then this line is removed in 'KVM: SVM: Support SEV-SNP AP Creation NAE event'. Should this line just be removed from this patch in the first place? > > > > /* > > diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h > > index 54ff56cb6125..3fd95193ed8d 100644 > > --- a/arch/x86/kvm/svm/svm.h > > +++ b/arch/x86/kvm/svm/svm.h > > @@ -79,19 +79,25 @@ struct kvm_sev_info { > > bool active; /* SEV enabled guest */ > > bool es_active; /* SEV-ES enabled guest */ > > bool snp_active; /* SEV-SNP enabled guest */ > > + > > unsigned int asid; /* ASID used for this guest */ > > unsigned int handle; /* SEV firmware handle */ > > int fd; /* SEV device fd */ > > + > > unsigned long pages_locked; /* Number of pages locked */ > > struct list_head regions_list; /* List of registered regions */ > > + > > u64 ap_jump_table; /* SEV-ES AP Jump Table address */ > > + > > struct kvm *enc_context_owner; /* Owner of copied encryption context */ > > struct list_head mirror_vms; /* List of VMs mirroring */ > > struct list_head mirror_entry; /* Use as a list entry of mirrors */ > > struct misc_cg *misc_cg; /* For misc cgroup accounting */ > > atomic_t migration_in_progress; > > + > > u64 snp_init_flags; > > void *snp_context; /* SNP guest context page */ > > + spinlock_t psc_lock; > > }; > > > > struct kvm_svm { > > @@ -702,6 +708,11 @@ void sev_es_prepare_switch_to_guest(struct sev_es_save_area *hostsa); > > void sev_es_unmap_ghcb(struct vcpu_svm *svm); > > struct page *snp_safe_alloc_page(struct kvm_vcpu *vcpu); > > void sev_rmp_page_level_adjust(struct kvm *kvm, kvm_pfn_t pfn, int *level); > > +int sev_post_map_gfn(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn); > > +void sev_post_unmap_gfn(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn); > > +void handle_rmp_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code); > > +void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu); > > +int sev_snp_update_protected_guest_state(struct kvm_vcpu *vcpu); Ditto should this be removed? > > > > /* vmenter.S */ > > > > -- > > 2.25.1 > >
On 11/17/2022 2:18 PM, Peter Gonda wrote: > On Wed, Aug 17, 2022 at 9:47 PM Alper Gun <alpergun@google.com> wrote: >> >> On Mon, Jun 20, 2022 at 4:12 PM Ashish Kalra <Ashish.Kalra@amd.com> wrote: >>> >>> From: Brijesh Singh <brijesh.singh@amd.com> >>> >>> When SEV-SNP is enabled in the guest VM, the guest memory pages can >>> either be a private or shared. A write from the hypervisor goes through >>> the RMP checks. If hardware sees that hypervisor is attempting to write >>> to a guest private page, then it triggers an RMP violation #PF. >>> >>> To avoid the RMP violation with GHCB pages, added new post_{map,unmap}_gfn >>> functions to verify if its safe to map GHCB pages. Uses a spinlock to >>> protect against the page state change for existing mapped pages. >>> >>> Need to add generic post_{map,unmap}_gfn() ops that can be used to verify >>> that its safe to map a given guest page in the hypervisor. >>> >>> This patch will need to be revisited later after consensus is reached on >>> how to manage guest private memory as probably UPM private memslots will >>> be able to handle this page state change more gracefully. >>> >>> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com> >>> Signed-off by: Ashish Kalra <ashish.kalra@amd.com> >>> --- >>> arch/x86/include/asm/kvm-x86-ops.h | 1 + >>> arch/x86/include/asm/kvm_host.h | 3 ++ >>> arch/x86/kvm/svm/sev.c | 48 ++++++++++++++++++++++++++++-- >>> arch/x86/kvm/svm/svm.c | 3 ++ >>> arch/x86/kvm/svm/svm.h | 11 +++++++ >>> 5 files changed, 64 insertions(+), 2 deletions(-) >>> >>> diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h >>> index e0068e702692..2dd2bc0cf4c3 100644 >>> --- a/arch/x86/include/asm/kvm-x86-ops.h >>> +++ b/arch/x86/include/asm/kvm-x86-ops.h >>> @@ -130,6 +130,7 @@ KVM_X86_OP(vcpu_deliver_sipi_vector) >>> KVM_X86_OP_OPTIONAL_RET0(vcpu_get_apicv_inhibit_reasons); >>> KVM_X86_OP(alloc_apic_backing_page) >>> KVM_X86_OP_OPTIONAL(rmp_page_level_adjust) >>> +KVM_X86_OP(update_protected_guest_state) >>> >>> #undef KVM_X86_OP >>> #undef KVM_X86_OP_OPTIONAL >>> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h >>> index 49b217dc8d7e..8abc0e724f5c 100644 >>> --- a/arch/x86/include/asm/kvm_host.h >>> +++ b/arch/x86/include/asm/kvm_host.h >>> @@ -1522,7 +1522,10 @@ struct kvm_x86_ops { >>> unsigned long (*vcpu_get_apicv_inhibit_reasons)(struct kvm_vcpu *vcpu); >>> >>> void *(*alloc_apic_backing_page)(struct kvm_vcpu *vcpu); >>> + >>> void (*rmp_page_level_adjust)(struct kvm *kvm, kvm_pfn_t pfn, int *level); >>> + >>> + int (*update_protected_guest_state)(struct kvm_vcpu *vcpu); >>> }; >>> >>> struct kvm_x86_nested_ops { >>> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c >>> index cb2d1bbb862b..4ed90331bca0 100644 >>> --- a/arch/x86/kvm/svm/sev.c >>> +++ b/arch/x86/kvm/svm/sev.c >>> @@ -341,6 +341,7 @@ static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp) >>> if (ret) >>> goto e_free; >>> >>> + spin_lock_init(&sev->psc_lock); >>> ret = sev_snp_init(&argp->error); >>> } else { >>> ret = sev_platform_init(&argp->error); >>> @@ -2828,19 +2829,28 @@ static inline int svm_map_ghcb(struct vcpu_svm *svm, struct kvm_host_map *map) >>> { >>> struct vmcb_control_area *control = &svm->vmcb->control; >>> u64 gfn = gpa_to_gfn(control->ghcb_gpa); >>> + struct kvm_vcpu *vcpu = &svm->vcpu; >>> >>> - if (kvm_vcpu_map(&svm->vcpu, gfn, map)) { >>> + if (kvm_vcpu_map(vcpu, gfn, map)) { >>> /* Unable to map GHCB from guest */ >>> pr_err("error mapping GHCB GFN [%#llx] from guest\n", gfn); >>> return -EFAULT; >>> } >>> >>> + if (sev_post_map_gfn(vcpu->kvm, map->gfn, map->pfn)) { >>> + kvm_vcpu_unmap(vcpu, map, false); >>> + return -EBUSY; >>> + } >>> + >>> return 0; >>> } >>> >>> static inline void svm_unmap_ghcb(struct vcpu_svm *svm, struct kvm_host_map *map) >>> { >>> - kvm_vcpu_unmap(&svm->vcpu, map, true); >>> + struct kvm_vcpu *vcpu = &svm->vcpu; >>> + >>> + kvm_vcpu_unmap(vcpu, map, true); >>> + sev_post_unmap_gfn(vcpu->kvm, map->gfn, map->pfn); >>> } >>> >>> static void dump_ghcb(struct vcpu_svm *svm) >>> @@ -3383,6 +3393,8 @@ static int __snp_handle_page_state_change(struct kvm_vcpu *vcpu, enum psc_op op, >>> return PSC_UNDEF_ERR; >>> } >>> >>> + spin_lock(&sev->psc_lock); >>> + >>> write_lock(&kvm->mmu_lock); >>> >>> rc = kvm_mmu_get_tdp_walk(vcpu, gpa, &pfn, &npt_level); >>> @@ -3417,6 +3429,8 @@ static int __snp_handle_page_state_change(struct kvm_vcpu *vcpu, enum psc_op op, >>> >>> write_unlock(&kvm->mmu_lock); >>> >>> + spin_unlock(&sev->psc_lock); >> >> There is a corner case where the psc_lock is not released. If >> kvm_mmu_get_tdp_walk fails, the lock will be kept and will cause soft >> lockup. >> >>> + >>> if (rc) { >>> pr_err_ratelimited("Error op %d gpa %llx pfn %llx level %d rc %d\n", >>> op, gpa, pfn, level, rc); >>> @@ -3965,3 +3979,33 @@ void sev_rmp_page_level_adjust(struct kvm *kvm, kvm_pfn_t pfn, int *level) >>> /* Adjust the level to keep the NPT and RMP in sync */ >>> *level = min_t(size_t, *level, rmp_level); >>> } >>> + >>> +int sev_post_map_gfn(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn) >>> +{ >>> + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; >>> + int level; >>> + >>> + if (!sev_snp_guest(kvm)) >>> + return 0; >>> + >>> + spin_lock(&sev->psc_lock); >>> + >>> + /* If pfn is not added as private then fail */ >>> + if (snp_lookup_rmpentry(pfn, &level) == 1) { >>> + spin_unlock(&sev->psc_lock); >>> + pr_err_ratelimited("failed to map private gfn 0x%llx pfn 0x%llx\n", gfn, pfn); >>> + return -EBUSY; >>> + } >>> + >>> + return 0; >>> +} >>> + >>> +void sev_post_unmap_gfn(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn) >>> +{ >>> + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; >>> + >>> + if (!sev_snp_guest(kvm)) >>> + return; >>> + >>> + spin_unlock(&sev->psc_lock); >>> +} >>> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c >>> index b24e0171cbf2..1c8e035ba011 100644 >>> --- a/arch/x86/kvm/svm/svm.c >>> +++ b/arch/x86/kvm/svm/svm.c >>> @@ -4734,7 +4734,10 @@ static struct kvm_x86_ops svm_x86_ops __initdata = { >>> .vcpu_get_apicv_inhibit_reasons = avic_vcpu_get_apicv_inhibit_reasons, >>> >>> .alloc_apic_backing_page = svm_alloc_apic_backing_page, >>> + >>> .rmp_page_level_adjust = sev_rmp_page_level_adjust, >>> + >>> + .update_protected_guest_state = sev_snp_update_protected_guest_state, >>> }; > > I don't see this function sev_snp_update_protected_guest_state() being > defined anywhere in this series. > > Then this line is removed in 'KVM: SVM: Support SEV-SNP AP Creation > NAE event'. Should this line just be removed from this patch in the > first place? Yes, already fixed for v7. > >>> >>> /* >>> diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h >>> index 54ff56cb6125..3fd95193ed8d 100644 >>> --- a/arch/x86/kvm/svm/svm.h >>> +++ b/arch/x86/kvm/svm/svm.h >>> @@ -79,19 +79,25 @@ struct kvm_sev_info { >>> bool active; /* SEV enabled guest */ >>> bool es_active; /* SEV-ES enabled guest */ >>> bool snp_active; /* SEV-SNP enabled guest */ >>> + >>> unsigned int asid; /* ASID used for this guest */ >>> unsigned int handle; /* SEV firmware handle */ >>> int fd; /* SEV device fd */ >>> + >>> unsigned long pages_locked; /* Number of pages locked */ >>> struct list_head regions_list; /* List of registered regions */ >>> + >>> u64 ap_jump_table; /* SEV-ES AP Jump Table address */ >>> + >>> struct kvm *enc_context_owner; /* Owner of copied encryption context */ >>> struct list_head mirror_vms; /* List of VMs mirroring */ >>> struct list_head mirror_entry; /* Use as a list entry of mirrors */ >>> struct misc_cg *misc_cg; /* For misc cgroup accounting */ >>> atomic_t migration_in_progress; >>> + >>> u64 snp_init_flags; >>> void *snp_context; /* SNP guest context page */ >>> + spinlock_t psc_lock; >>> }; >>> >>> struct kvm_svm { >>> @@ -702,6 +708,11 @@ void sev_es_prepare_switch_to_guest(struct sev_es_save_area *hostsa); >>> void sev_es_unmap_ghcb(struct vcpu_svm *svm); >>> struct page *snp_safe_alloc_page(struct kvm_vcpu *vcpu); >>> void sev_rmp_page_level_adjust(struct kvm *kvm, kvm_pfn_t pfn, int *level); >>> +int sev_post_map_gfn(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn); >>> +void sev_post_unmap_gfn(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn); >>> +void handle_rmp_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code); >>> +void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu); >>> +int sev_snp_update_protected_guest_state(struct kvm_vcpu *vcpu); > > Ditto should this be removed? > Yes, already fixed for v7. Thanks, Ashish >>> >>> /* vmenter.S */ >>> >>> -- >>> 2.25.1 >>>
On 11/17/2022 2:18 PM, Peter Gonda wrote: > On Wed, Aug 17, 2022 at 9:47 PM Alper Gun <alpergun@google.com> wrote: >> >> On Mon, Jun 20, 2022 at 4:12 PM Ashish Kalra <Ashish.Kalra@amd.com> wrote: >>> >>> From: Brijesh Singh <brijesh.singh@amd.com> >>> >>> When SEV-SNP is enabled in the guest VM, the guest memory pages can >>> either be a private or shared. A write from the hypervisor goes through >>> the RMP checks. If hardware sees that hypervisor is attempting to write >>> to a guest private page, then it triggers an RMP violation #PF. >>> >>> To avoid the RMP violation with GHCB pages, added new post_{map,unmap}_gfn >>> functions to verify if its safe to map GHCB pages. Uses a spinlock to >>> protect against the page state change for existing mapped pages. >>> >>> Need to add generic post_{map,unmap}_gfn() ops that can be used to verify >>> that its safe to map a given guest page in the hypervisor. >>> >>> This patch will need to be revisited later after consensus is reached on >>> how to manage guest private memory as probably UPM private memslots will >>> be able to handle this page state change more gracefully. >>> >>> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com> >>> Signed-off by: Ashish Kalra <ashish.kalra@amd.com> >>> --- >>> arch/x86/include/asm/kvm-x86-ops.h | 1 + >>> arch/x86/include/asm/kvm_host.h | 3 ++ >>> arch/x86/kvm/svm/sev.c | 48 ++++++++++++++++++++++++++++-- >>> arch/x86/kvm/svm/svm.c | 3 ++ >>> arch/x86/kvm/svm/svm.h | 11 +++++++ >>> 5 files changed, 64 insertions(+), 2 deletions(-) >>> >>> diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h >>> index e0068e702692..2dd2bc0cf4c3 100644 >>> --- a/arch/x86/include/asm/kvm-x86-ops.h >>> +++ b/arch/x86/include/asm/kvm-x86-ops.h >>> @@ -130,6 +130,7 @@ KVM_X86_OP(vcpu_deliver_sipi_vector) >>> KVM_X86_OP_OPTIONAL_RET0(vcpu_get_apicv_inhibit_reasons); >>> KVM_X86_OP(alloc_apic_backing_page) >>> KVM_X86_OP_OPTIONAL(rmp_page_level_adjust) >>> +KVM_X86_OP(update_protected_guest_state) >>> >>> #undef KVM_X86_OP >>> #undef KVM_X86_OP_OPTIONAL >>> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h >>> index 49b217dc8d7e..8abc0e724f5c 100644 >>> --- a/arch/x86/include/asm/kvm_host.h >>> +++ b/arch/x86/include/asm/kvm_host.h >>> @@ -1522,7 +1522,10 @@ struct kvm_x86_ops { >>> unsigned long (*vcpu_get_apicv_inhibit_reasons)(struct kvm_vcpu *vcpu); >>> >>> void *(*alloc_apic_backing_page)(struct kvm_vcpu *vcpu); >>> + >>> void (*rmp_page_level_adjust)(struct kvm *kvm, kvm_pfn_t pfn, int *level); >>> + >>> + int (*update_protected_guest_state)(struct kvm_vcpu *vcpu); >>> }; >>> >>> struct kvm_x86_nested_ops { >>> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c >>> index cb2d1bbb862b..4ed90331bca0 100644 >>> --- a/arch/x86/kvm/svm/sev.c >>> +++ b/arch/x86/kvm/svm/sev.c >>> @@ -341,6 +341,7 @@ static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp) >>> if (ret) >>> goto e_free; >>> >>> + spin_lock_init(&sev->psc_lock); >>> ret = sev_snp_init(&argp->error); >>> } else { >>> ret = sev_platform_init(&argp->error); >>> @@ -2828,19 +2829,28 @@ static inline int svm_map_ghcb(struct vcpu_svm *svm, struct kvm_host_map *map) >>> { >>> struct vmcb_control_area *control = &svm->vmcb->control; >>> u64 gfn = gpa_to_gfn(control->ghcb_gpa); >>> + struct kvm_vcpu *vcpu = &svm->vcpu; >>> >>> - if (kvm_vcpu_map(&svm->vcpu, gfn, map)) { >>> + if (kvm_vcpu_map(vcpu, gfn, map)) { >>> /* Unable to map GHCB from guest */ >>> pr_err("error mapping GHCB GFN [%#llx] from guest\n", gfn); >>> return -EFAULT; >>> } >>> >>> + if (sev_post_map_gfn(vcpu->kvm, map->gfn, map->pfn)) { >>> + kvm_vcpu_unmap(vcpu, map, false); >>> + return -EBUSY; >>> + } >>> + >>> return 0; >>> } >>> >>> static inline void svm_unmap_ghcb(struct vcpu_svm *svm, struct kvm_host_map *map) >>> { >>> - kvm_vcpu_unmap(&svm->vcpu, map, true); >>> + struct kvm_vcpu *vcpu = &svm->vcpu; >>> + >>> + kvm_vcpu_unmap(vcpu, map, true); >>> + sev_post_unmap_gfn(vcpu->kvm, map->gfn, map->pfn); >>> } >>> >>> static void dump_ghcb(struct vcpu_svm *svm) >>> @@ -3383,6 +3393,8 @@ static int __snp_handle_page_state_change(struct kvm_vcpu *vcpu, enum psc_op op, >>> return PSC_UNDEF_ERR; >>> } >>> >>> + spin_lock(&sev->psc_lock); >>> + >>> write_lock(&kvm->mmu_lock); >>> >>> rc = kvm_mmu_get_tdp_walk(vcpu, gpa, &pfn, &npt_level); >>> @@ -3417,6 +3429,8 @@ static int __snp_handle_page_state_change(struct kvm_vcpu *vcpu, enum psc_op op, >>> >>> write_unlock(&kvm->mmu_lock); >>> >>> + spin_unlock(&sev->psc_lock); >> >> There is a corner case where the psc_lock is not released. If >> kvm_mmu_get_tdp_walk fails, the lock will be kept and will cause soft >> lockup. >> This is also already fixed for v7. Thanks, Ashish
diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h index e0068e702692..2dd2bc0cf4c3 100644 --- a/arch/x86/include/asm/kvm-x86-ops.h +++ b/arch/x86/include/asm/kvm-x86-ops.h @@ -130,6 +130,7 @@ KVM_X86_OP(vcpu_deliver_sipi_vector) KVM_X86_OP_OPTIONAL_RET0(vcpu_get_apicv_inhibit_reasons); KVM_X86_OP(alloc_apic_backing_page) KVM_X86_OP_OPTIONAL(rmp_page_level_adjust) +KVM_X86_OP(update_protected_guest_state) #undef KVM_X86_OP #undef KVM_X86_OP_OPTIONAL diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 49b217dc8d7e..8abc0e724f5c 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1522,7 +1522,10 @@ struct kvm_x86_ops { unsigned long (*vcpu_get_apicv_inhibit_reasons)(struct kvm_vcpu *vcpu); void *(*alloc_apic_backing_page)(struct kvm_vcpu *vcpu); + void (*rmp_page_level_adjust)(struct kvm *kvm, kvm_pfn_t pfn, int *level); + + int (*update_protected_guest_state)(struct kvm_vcpu *vcpu); }; struct kvm_x86_nested_ops { diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index cb2d1bbb862b..4ed90331bca0 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -341,6 +341,7 @@ static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp) if (ret) goto e_free; + spin_lock_init(&sev->psc_lock); ret = sev_snp_init(&argp->error); } else { ret = sev_platform_init(&argp->error); @@ -2828,19 +2829,28 @@ static inline int svm_map_ghcb(struct vcpu_svm *svm, struct kvm_host_map *map) { struct vmcb_control_area *control = &svm->vmcb->control; u64 gfn = gpa_to_gfn(control->ghcb_gpa); + struct kvm_vcpu *vcpu = &svm->vcpu; - if (kvm_vcpu_map(&svm->vcpu, gfn, map)) { + if (kvm_vcpu_map(vcpu, gfn, map)) { /* Unable to map GHCB from guest */ pr_err("error mapping GHCB GFN [%#llx] from guest\n", gfn); return -EFAULT; } + if (sev_post_map_gfn(vcpu->kvm, map->gfn, map->pfn)) { + kvm_vcpu_unmap(vcpu, map, false); + return -EBUSY; + } + return 0; } static inline void svm_unmap_ghcb(struct vcpu_svm *svm, struct kvm_host_map *map) { - kvm_vcpu_unmap(&svm->vcpu, map, true); + struct kvm_vcpu *vcpu = &svm->vcpu; + + kvm_vcpu_unmap(vcpu, map, true); + sev_post_unmap_gfn(vcpu->kvm, map->gfn, map->pfn); } static void dump_ghcb(struct vcpu_svm *svm) @@ -3383,6 +3393,8 @@ static int __snp_handle_page_state_change(struct kvm_vcpu *vcpu, enum psc_op op, return PSC_UNDEF_ERR; } + spin_lock(&sev->psc_lock); + write_lock(&kvm->mmu_lock); rc = kvm_mmu_get_tdp_walk(vcpu, gpa, &pfn, &npt_level); @@ -3417,6 +3429,8 @@ static int __snp_handle_page_state_change(struct kvm_vcpu *vcpu, enum psc_op op, write_unlock(&kvm->mmu_lock); + spin_unlock(&sev->psc_lock); + if (rc) { pr_err_ratelimited("Error op %d gpa %llx pfn %llx level %d rc %d\n", op, gpa, pfn, level, rc); @@ -3965,3 +3979,33 @@ void sev_rmp_page_level_adjust(struct kvm *kvm, kvm_pfn_t pfn, int *level) /* Adjust the level to keep the NPT and RMP in sync */ *level = min_t(size_t, *level, rmp_level); } + +int sev_post_map_gfn(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn) +{ + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; + int level; + + if (!sev_snp_guest(kvm)) + return 0; + + spin_lock(&sev->psc_lock); + + /* If pfn is not added as private then fail */ + if (snp_lookup_rmpentry(pfn, &level) == 1) { + spin_unlock(&sev->psc_lock); + pr_err_ratelimited("failed to map private gfn 0x%llx pfn 0x%llx\n", gfn, pfn); + return -EBUSY; + } + + return 0; +} + +void sev_post_unmap_gfn(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn) +{ + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; + + if (!sev_snp_guest(kvm)) + return; + + spin_unlock(&sev->psc_lock); +} diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index b24e0171cbf2..1c8e035ba011 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -4734,7 +4734,10 @@ static struct kvm_x86_ops svm_x86_ops __initdata = { .vcpu_get_apicv_inhibit_reasons = avic_vcpu_get_apicv_inhibit_reasons, .alloc_apic_backing_page = svm_alloc_apic_backing_page, + .rmp_page_level_adjust = sev_rmp_page_level_adjust, + + .update_protected_guest_state = sev_snp_update_protected_guest_state, }; /* diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index 54ff56cb6125..3fd95193ed8d 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -79,19 +79,25 @@ struct kvm_sev_info { bool active; /* SEV enabled guest */ bool es_active; /* SEV-ES enabled guest */ bool snp_active; /* SEV-SNP enabled guest */ + unsigned int asid; /* ASID used for this guest */ unsigned int handle; /* SEV firmware handle */ int fd; /* SEV device fd */ + unsigned long pages_locked; /* Number of pages locked */ struct list_head regions_list; /* List of registered regions */ + u64 ap_jump_table; /* SEV-ES AP Jump Table address */ + struct kvm *enc_context_owner; /* Owner of copied encryption context */ struct list_head mirror_vms; /* List of VMs mirroring */ struct list_head mirror_entry; /* Use as a list entry of mirrors */ struct misc_cg *misc_cg; /* For misc cgroup accounting */ atomic_t migration_in_progress; + u64 snp_init_flags; void *snp_context; /* SNP guest context page */ + spinlock_t psc_lock; }; struct kvm_svm { @@ -702,6 +708,11 @@ void sev_es_prepare_switch_to_guest(struct sev_es_save_area *hostsa); void sev_es_unmap_ghcb(struct vcpu_svm *svm); struct page *snp_safe_alloc_page(struct kvm_vcpu *vcpu); void sev_rmp_page_level_adjust(struct kvm *kvm, kvm_pfn_t pfn, int *level); +int sev_post_map_gfn(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn); +void sev_post_unmap_gfn(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn); +void handle_rmp_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u64 error_code); +void sev_snp_init_protected_guest_state(struct kvm_vcpu *vcpu); +int sev_snp_update_protected_guest_state(struct kvm_vcpu *vcpu); /* vmenter.S */