[PATCH v6 1/3] x86/sev: Add new dump_rmp parameter to snp_leak_pages() API

Ashish Kalra
2025-09-16T21:29:33Z

When leaking certain page types, such as Hypervisor Fixed (HV_FIXED)
pages, it does not make sense to dump RMP contents for the 2MB range of
the page(s) being leaked. In the case of HV_FIXED pages, this is not an
error situation where the surrounding 2MB page RMP entries can provide
debug information.

Add new __snp_leak_pages() API with dump_rmp bool parameter to support
continue adding pages to the snp_leaked_pages_list but not issue
dump_rmpentry().

Make snp_leak_pages() a wrapper for the common case which also allows
existing users to continue to dump RMP entries.

Suggested-by: Thomas Lendacky <Thomas.Lendacky@amd.com>
Suggested-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Acked-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
---
arch/x86/include/asm/sev.h | 7 ++++++-
arch/x86/virt/svm/sev.c | 7 ++++---
2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index da2cee884fce..0e6c0940100f 100644
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -654,9 +654,13 @@ void snp_dump_hva_rmpentry(unsigned long address);
int psmash(u64 pfn);
int rmp_make_private(u64 pfn, u64 gpa, enum pg_level level, u32 asid, bool immutable);
int rmp_make_shared(u64 pfn, enum pg_level level);
-void snp_leak_pages(u64 pfn, unsigned int npages);
+void __snp_leak_pages(u64 pfn, unsigned int npages, bool dump_rmp);
void kdump_sev_callback(void);
void snp_fixup_e820_tables(void);
+static inline void snp_leak_pages(u64 pfn, unsigned int pages)
+{
+ __snp_leak_pages(pfn, pages, true);
+}
#else
static inline bool snp_probe_rmptable_info(void) { return false; }
static inline int snp_rmptable_init(void) { return -ENOSYS; }
@@ -669,6 +673,7 @@ static inline int rmp_make_private(u64 pfn, u64 gpa, enum pg_level level, u32 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, bool dump_rmp) {}
static inline void snp_leak_pages(u64 pfn, unsigned int npages) {}
static inline void kdump_sev_callback(void) { }
static inline void snp_fixup_e820_tables(void) {}
diff --git a/arch/x86/virt/svm/sev.c b/arch/x86/virt/svm/sev.c
index 942372e69b4d..ee643a6cd691 100644
--- a/arch/x86/virt/svm/sev.c
+++ b/arch/x86/virt/svm/sev.c
@@ -1029,7 +1029,7 @@ int rmp_make_shared(u64 pfn, enum pg_level level)
}
EXPORT_SYMBOL_GPL(rmp_make_shared);

-void snp_leak_pages(u64 pfn, unsigned int npages)
+void __snp_leak_pages(u64 pfn, unsigned int npages, bool dump_rmp)
{
struct page *page = pfn_to_page(pfn);

@@ -1052,14 +1052,15 @@ void snp_leak_pages(u64 pfn, unsigned int npages)
(PageHead(page) && compound_nr(page) <= npages))
list_add_tail(&page->buddy_list, &snp_leaked_pages_list);

- dump_rmpentry(pfn);
+ if (dump_rmp)
+ dump_rmpentry(pfn);
snp_nr_leaked_pages++;
pfn++;
page++;
}
spin_unlock(&snp_leaked_pages_list_lock);
}
-EXPORT_SYMBOL_GPL(snp_leak_pages);
+EXPORT_SYMBOL_GPL(__snp_leak_pages);

void kdump_sev_callback(void)
{
--
2.34.1