| Message ID | 20240126041126.1927228-16-michael.roth@amd.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Add AMD Secure Nested Paging (SEV-SNP) Initialization Support | expand |
On 1/26/24 05:11, Michael Roth wrote: > From: Ashish Kalra <ashish.kalra@amd.com> > > Pages are unsafe to be released back to the page-allocator, if they > have been transitioned to firmware/guest state and can't be reclaimed > or transitioned back to hypervisor/shared state. In this case add > them to an internal leaked pages list to ensure that they are not freed > or touched/accessed to cause fatal page faults. > > Suggested-by: Vlastimil Babka <vbabka@suse.cz> > Signed-off-by: Ashish Kalra <ashish.kalra@amd.com> > [mdr: relocate to arch/x86/virt/svm/sev.c] > Signed-off-by: Michael Roth <michael.roth@amd.com> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Some minor nitpicks: > --- > arch/x86/include/asm/sev.h | 2 ++ > arch/x86/virt/svm/sev.c | 34 ++++++++++++++++++++++++++++++++++ > 2 files changed, 36 insertions(+) > > diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h > index d3ccb7a0c7e9..435ba9bc4510 100644 > --- a/arch/x86/include/asm/sev.h > +++ b/arch/x86/include/asm/sev.h > @@ -264,6 +264,7 @@ void snp_dump_hva_rmpentry(unsigned long address); > int psmash(u64 pfn); > int rmp_make_private(u64 pfn, u64 gpa, enum pg_level level, int asid, bool immutable); > int rmp_make_shared(u64 pfn, enum pg_level level); > +void snp_leak_pages(u64 pfn, unsigned int npages); > #else > static inline bool snp_probe_rmptable_info(void) { return false; } > static inline int snp_lookup_rmpentry(u64 pfn, bool *assigned, int *level) { return -ENODEV; } > @@ -275,6 +276,7 @@ static inline int rmp_make_private(u64 pfn, u64 gpa, enum pg_level level, int as > return -ENODEV; > } > static inline int rmp_make_shared(u64 pfn, enum pg_level level) { return -ENODEV; } > +static inline void snp_leak_pages(u64 pfn, unsigned int npages) {} > #endif > > #endif > diff --git a/arch/x86/virt/svm/sev.c b/arch/x86/virt/svm/sev.c > index 1a13eff78c9d..649ac1bb6b0e 100644 > --- a/arch/x86/virt/svm/sev.c > +++ b/arch/x86/virt/svm/sev.c > @@ -65,6 +65,11 @@ static u64 probed_rmp_base, probed_rmp_size; > static struct rmpentry *rmptable __ro_after_init; > static u64 rmptable_max_pfn __ro_after_init; > > +static LIST_HEAD(snp_leaked_pages_list); > +static DEFINE_SPINLOCK(snp_leaked_pages_list_lock); > + > +static unsigned long snp_nr_leaked_pages; > + > #undef pr_fmt > #define pr_fmt(fmt) "SEV-SNP: " fmt > > @@ -505,3 +510,32 @@ int rmp_make_shared(u64 pfn, enum pg_level level) > return rmpupdate(pfn, &state); > } > EXPORT_SYMBOL_GPL(rmp_make_shared); > + > +void snp_leak_pages(u64 pfn, unsigned int npages) > +{ > + struct page *page = pfn_to_page(pfn); > + > + pr_warn("Leaking PFN range 0x%llx-0x%llx\n", pfn, pfn + npages); > + > + spin_lock(&snp_leaked_pages_list_lock); > + while (npages--) { > + /* > + * Reuse the page's buddy list for chaining into the leaked > + * pages list. This page should not be on a free list currently > + * and is also unsafe to be added to a free list. > + */ > + if (likely(!PageCompound(page)) || > + (PageHead(page) && compound_nr(page) <= npages)) > + /* > + * Skip inserting tail pages of compound page as > + * page->buddy_list of tail pages is not usable. > + */ > + list_add_tail(&page->buddy_list, &snp_leaked_pages_list); Even though it's not necessary for correctness, with the comment I'd put the whole block into { } to make easier to follow. Or just move the comment above the if() itself? > + dump_rmpentry(pfn); > + snp_nr_leaked_pages++; > + pfn++; > + page++; > + } > + spin_unlock(&snp_leaked_pages_list_lock); > +} > +EXPORT_SYMBOL_GPL(snp_leak_pages);
On Mon, Jan 29, 2024 at 03:26:29PM +0100, Vlastimil Babka wrote: > Reviewed-by: Vlastimil Babka <vbabka@suse.cz> > > Some minor nitpicks: Thanks, here's what I have applied: commit c3875aff4e0739a6af385795470da70d675a7635 Author: Ashish Kalra <ashish.kalra@amd.com> Date: Thu Jan 25 22:11:15 2024 -0600 x86/sev: Introduce an SNP leaked pages list Pages are unsafe to be released back to the page-allocator if they have been transitioned to firmware/guest state and can't be reclaimed or transitioned back to hypervisor/shared state. In this case, add them to an internal leaked pages list to ensure that they are not freed or touched/accessed to cause fatal page faults. [ mdr: Relocate to arch/x86/virt/svm/sev.c ] Suggested-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Ashish Kalra <ashish.kalra@amd.com> Signed-off-by: Michael Roth <michael.roth@amd.com> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Link: https://lore.kernel.org/r/20240126041126.1927228-16-michael.roth@amd.com diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index d3ccb7a0c7e9..435ba9bc4510 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -264,6 +264,7 @@ void snp_dump_hva_rmpentry(unsigned long address); int psmash(u64 pfn); int rmp_make_private(u64 pfn, u64 gpa, enum pg_level level, int asid, bool immutable); int rmp_make_shared(u64 pfn, enum pg_level level); +void snp_leak_pages(u64 pfn, unsigned int npages); #else static inline bool snp_probe_rmptable_info(void) { return false; } static inline int snp_lookup_rmpentry(u64 pfn, bool *assigned, int *level) { return -ENODEV; } @@ -275,6 +276,7 @@ static inline int rmp_make_private(u64 pfn, u64 gpa, enum pg_level level, int as return -ENODEV; } static inline int rmp_make_shared(u64 pfn, enum pg_level level) { return -ENODEV; } +static inline void snp_leak_pages(u64 pfn, unsigned int npages) {} #endif #endif diff --git a/arch/x86/virt/svm/sev.c b/arch/x86/virt/svm/sev.c index f1be56555ee6..901863a842d7 100644 --- a/arch/x86/virt/svm/sev.c +++ b/arch/x86/virt/svm/sev.c @@ -65,6 +65,11 @@ static u64 probed_rmp_base, probed_rmp_size; static struct rmpentry *rmptable __ro_after_init; static u64 rmptable_max_pfn __ro_after_init; +static LIST_HEAD(snp_leaked_pages_list); +static DEFINE_SPINLOCK(snp_leaked_pages_list_lock); + +static unsigned long snp_nr_leaked_pages; + #undef pr_fmt #define pr_fmt(fmt) "SEV-SNP: " fmt @@ -515,3 +520,35 @@ int rmp_make_shared(u64 pfn, enum pg_level level) return rmpupdate(pfn, &state); } EXPORT_SYMBOL_GPL(rmp_make_shared); + +void snp_leak_pages(u64 pfn, unsigned int npages) +{ + struct page *page = pfn_to_page(pfn); + + pr_warn("Leaking PFN range 0x%llx-0x%llx\n", pfn, pfn + npages); + + spin_lock(&snp_leaked_pages_list_lock); + while (npages--) { + + /* + * Reuse the page's buddy list for chaining into the leaked + * pages list. This page should not be on a free list currently + * and is also unsafe to be added to a free list. + */ + if (likely(!PageCompound(page)) || + + /* + * Skip inserting tail pages of compound page as + * page->buddy_list of tail pages is not usable. + */ + (PageHead(page) && compound_nr(page) <= npages)) + list_add_tail(&page->buddy_list, &snp_leaked_pages_list); + + dump_rmpentry(pfn); + snp_nr_leaked_pages++; + pfn++; + page++; + } + spin_unlock(&snp_leaked_pages_list_lock); +} +EXPORT_SYMBOL_GPL(snp_leak_pages);
diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index d3ccb7a0c7e9..435ba9bc4510 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -264,6 +264,7 @@ void snp_dump_hva_rmpentry(unsigned long address); int psmash(u64 pfn); int rmp_make_private(u64 pfn, u64 gpa, enum pg_level level, int asid, bool immutable); int rmp_make_shared(u64 pfn, enum pg_level level); +void snp_leak_pages(u64 pfn, unsigned int npages); #else static inline bool snp_probe_rmptable_info(void) { return false; } static inline int snp_lookup_rmpentry(u64 pfn, bool *assigned, int *level) { return -ENODEV; } @@ -275,6 +276,7 @@ static inline int rmp_make_private(u64 pfn, u64 gpa, enum pg_level level, int as return -ENODEV; } static inline int rmp_make_shared(u64 pfn, enum pg_level level) { return -ENODEV; } +static inline void snp_leak_pages(u64 pfn, unsigned int npages) {} #endif #endif diff --git a/arch/x86/virt/svm/sev.c b/arch/x86/virt/svm/sev.c index 1a13eff78c9d..649ac1bb6b0e 100644 --- a/arch/x86/virt/svm/sev.c +++ b/arch/x86/virt/svm/sev.c @@ -65,6 +65,11 @@ static u64 probed_rmp_base, probed_rmp_size; static struct rmpentry *rmptable __ro_after_init; static u64 rmptable_max_pfn __ro_after_init; +static LIST_HEAD(snp_leaked_pages_list); +static DEFINE_SPINLOCK(snp_leaked_pages_list_lock); + +static unsigned long snp_nr_leaked_pages; + #undef pr_fmt #define pr_fmt(fmt) "SEV-SNP: " fmt @@ -505,3 +510,32 @@ int rmp_make_shared(u64 pfn, enum pg_level level) return rmpupdate(pfn, &state); } EXPORT_SYMBOL_GPL(rmp_make_shared); + +void snp_leak_pages(u64 pfn, unsigned int npages) +{ + struct page *page = pfn_to_page(pfn); + + pr_warn("Leaking PFN range 0x%llx-0x%llx\n", pfn, pfn + npages); + + spin_lock(&snp_leaked_pages_list_lock); + while (npages--) { + /* + * Reuse the page's buddy list for chaining into the leaked + * pages list. This page should not be on a free list currently + * and is also unsafe to be added to a free list. + */ + if (likely(!PageCompound(page)) || + (PageHead(page) && compound_nr(page) <= npages)) + /* + * Skip inserting tail pages of compound page as + * page->buddy_list of tail pages is not usable. + */ + list_add_tail(&page->buddy_list, &snp_leaked_pages_list); + dump_rmpentry(pfn); + snp_nr_leaked_pages++; + pfn++; + page++; + } + spin_unlock(&snp_leaked_pages_list_lock); +} +EXPORT_SYMBOL_GPL(snp_leak_pages);