[PATCH v1 15/26] x86/sev: Introduce snp leaked pages list
From: Michael Roth <hidden>
Date: 2023-12-30 16:23:54
Also in:
kvm, linux-crypto, linux-mm, lkml
Subsystem:
the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
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. Signed-off-by: Ashish Kalra <ashish.kalra@amd.com> [mdr: relocate to arch/x86/virt/svm/sev.c] Signed-off-by: Michael Roth <redacted> --- arch/x86/include/asm/sev.h | 2 ++ arch/x86/virt/svm/sev.c | 35 +++++++++++++++++++++++++++++++++++ 2 files changed, 37 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 ee182351d93a..0f2e1ce241b5 100644
--- a/arch/x86/virt/svm/sev.c
+++ b/arch/x86/virt/svm/sev.c@@ -60,6 +60,17 @@ static u64 probed_rmp_base, probed_rmp_size; static struct rmpentry *rmptable __ro_after_init; static u64 rmptable_max_pfn __ro_after_init; +/* List of pages which are leaked and cannot be reclaimed */ +struct leaked_page { + struct page *page; + struct list_head list; +}; + +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
@@ -476,3 +487,27 @@ 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); + struct leaked_page *leak; + + pr_debug("%s: leaking PFN range 0x%llx-0x%llx\n", __func__, pfn, pfn + npages); + + spin_lock(&snp_leaked_pages_list_lock); + while (npages--) { + leak = kzalloc(sizeof(*leak), GFP_KERNEL_ACCOUNT); + if (!leak) + goto unlock; + leak->page = page; + list_add_tail(&leak->list, &snp_leaked_pages_list); + dump_rmpentry(pfn); + snp_nr_leaked_pages++; + pfn++; + page++; + } +unlock: + spin_unlock(&snp_leaked_pages_list_lock); +} +EXPORT_SYMBOL_GPL(snp_leak_pages);
--
2.25.1