linux-kernel - [PATCH v2 1/3] x86/sev: Add new quiet parameter to snp_leak

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Message-ID: <7f7cdb3268e95b7dfa924c3da16a201da0b095f3.1755545773.git.ashish.kalra@amd.com>
Date: Mon, 18 Aug 2025 19:58:38 +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>,
	<michael.roth@....com>, <Neeraj.Upadhyay@....com>,
	<linux-kernel@...r.kernel.org>, <kvm@...r.kernel.org>,
	<linux-crypto@...r.kernel.org>
Subject: [PATCH v2 1/3] x86/sev: Add new quiet 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 quiet parameter to snp_leak_pages(), to continue adding pages
to the snp_leaked_pages_list but not issue dump_rmpentry().

All existing users pass quiet=false parameter maintaining current
behavior. No functional changes.

Suggested-by: Thomas Lendacky <Thomas.Lendacky@....com>
Signed-off-by: Ashish Kalra <ashish.kalra@....com>
---
 arch/x86/include/asm/sev.h   | 4 ++--
 arch/x86/kvm/svm/sev.c       | 4 ++--
 arch/x86/virt/svm/sev.c      | 5 +++--
 drivers/crypto/ccp/sev-dev.c | 2 +-
 4 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index 02236962fdb1..8fc03f6c3026 100644
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -616,7 +616,7 @@ void snp_dump_hva_rmpentry(unsigned long address);
 int psmash(u64 pfn);
 int rmp_make_private(u64 pfn, u64 gpa, enum pg_level level, 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 quiet);
 void kdump_sev_callback(void);
 void snp_fixup_e820_tables(void);
 
@@ -649,7 +649,7 @@ 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) {}
+static inline void snp_leak_pages(u64 pfn, unsigned int npages, bool quiet) {}
 static inline void kdump_sev_callback(void) { }
 static inline void snp_fixup_e820_tables(void) {}
 static inline void sev_evict_cache(void *va, int npages) {}
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 2fbdebf79fbb..a7db96a5f56d 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -271,7 +271,7 @@ static void sev_decommission(unsigned int handle)
 static int kvm_rmp_make_shared(struct kvm *kvm, u64 pfn, enum pg_level level)
 {
 	if (KVM_BUG_ON(rmp_make_shared(pfn, level), kvm)) {
-		snp_leak_pages(pfn, page_level_size(level) >> PAGE_SHIFT);
+		snp_leak_pages(pfn, page_level_size(level) >> PAGE_SHIFT, false);
 		return -EIO;
 	}
 
@@ -300,7 +300,7 @@ static int snp_page_reclaim(struct kvm *kvm, u64 pfn)
 	data.paddr = __sme_set(pfn << PAGE_SHIFT);
 	rc = sev_do_cmd(SEV_CMD_SNP_PAGE_RECLAIM, &data, &fw_err);
 	if (KVM_BUG(rc, kvm, "Failed to reclaim PFN %llx, rc %d fw_err %d", pfn, rc, fw_err)) {
-		snp_leak_pages(pfn, 1);
+		snp_leak_pages(pfn, 1, false);
 		return -EIO;
 	}
 
diff --git a/arch/x86/virt/svm/sev.c b/arch/x86/virt/svm/sev.c
index 942372e69b4d..d75659859a07 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 quiet)
 {
 	struct page *page = pfn_to_page(pfn);
 
@@ -1052,7 +1052,8 @@ 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 (!quiet)
+			dump_rmpentry(pfn);
 		snp_nr_leaked_pages++;
 		pfn++;
 		page++;
diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index 4f000dc2e639..203a43a2df63 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -408,7 +408,7 @@ static int snp_reclaim_pages(unsigned long paddr, unsigned int npages, bool lock
 	 * If there was a failure reclaiming the page then it is no longer safe
 	 * to release it back to the system; leak it instead.
 	 */
-	snp_leak_pages(__phys_to_pfn(paddr), npages - i);
+	snp_leak_pages(__phys_to_pfn(paddr), npages - i, false);
 	return ret;
 }
 
-- 
2.34.1