linux-kernel - [PATCH v3 1/3] x86/sev: Add new dump_rmp parameter to snp_leak

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Message-ID: <b5ed57029ae3d5c5eeac57faf4de9b95ae7af0b5.1755727173.git.ashish.kalra@amd.com>
Date: Wed, 20 Aug 2025 22:19:16 +0000
From: Ashish Kalra <Ashish.Kalra@....com>
To: <tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
	<dave.hansen@...ux.intel.com>, <x86@...nel.org>, <hpa@...or.com>,
	<seanjc@...gle.com>, <pbonzini@...hat.com>, <thomas.lendacky@....com>,
	<herbert@...dor.apana.org.au>
CC: <nikunj@....com>, <davem@...emloft.net>, <aik@....com>, <ardb@...nel.org>,
	<john.allen@....com>, <michael.roth@....com>, <Neeraj.Upadhyay@....com>,
	<linux-kernel@...r.kernel.org>, <kvm@...r.kernel.org>,
	<linux-crypto@...r.kernel.org>
Subject: [PATCH v3 1/3] x86/sev: Add new dump_rmp parameter to snp_leak_pages() API

From: Ashish Kalra <ashish.kalra@....com>

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@....com>
Suggested-by: Sean Christopherson <seanjc@...gle.com>
Signed-off-by: Ashish Kalra <ashish.kalra@....com>
---
 arch/x86/include/asm/sev.h | 8 +++++++-
 arch/x86/virt/svm/sev.c    | 7 ++++---
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index 02236962fdb1..0d14bc955a0a 100644
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -616,10 +616,15 @@ 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);
+}
+
 static inline void sev_evict_cache(void *va, int npages)
 {
 	volatile u8 val __always_unused;
@@ -649,6 +654,7 @@ 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