The following commit has been merged into the x86/sev branch of tip:

Commit-ID:     cca149429956745293ea94865ff8be6f77cc003d
Gitweb:        https://git.kernel.org/tip/cca149429956745293ea94865ff8be6f77cc003d
Author:        Tom Lendacky <thomas.lendacky@amd.com>
AuthorDate:    Mon, 09 Mar 2026 12:00:45 -06:00
Committer:     Borislav Petkov (AMD) <bp@alien8.de>
CommitterDate: Mon, 09 Mar 2026 21:49:18 +01:00

x86/virt/sev: Keep the RMP table bookkeeping area mapped

In preparation for delayed SNP initialization and disablement on shutdown, the
RMP will need to be cleared each time SNP is disabled. Maintain the mapping to
the RMP bookkeeping area to avoid mapping and unmapping it each time and any
possible errors that may arise from that.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Tycho Andersen (AMD) <tycho@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://patch.msgid.link/20260309180053.2389118-4-tycho@kernel.org
---
 arch/x86/virt/svm/sev.c | 40 +++++++++++++++++-----------------------
 1 file changed, 17 insertions(+), 23 deletions(-)

diff --git a/arch/x86/virt/svm/sev.c b/arch/x86/virt/svm/sev.c
index 5e07f10..e35fac0 100644
--- a/arch/x86/virt/svm/sev.c
+++ b/arch/x86/virt/svm/sev.c
@@ -117,6 +117,8 @@ static u64 rmp_segment_mask;
 
 static u64 rmp_cfg;
 
+static void *rmp_bookkeeping __ro_after_init;
+
 /* Mask to apply to a PFN to get the first PFN of a 2MB page */
 #define PFN_PMD_MASK	GENMASK_ULL(63, PMD_SHIFT - PAGE_SHIFT)
 
@@ -240,23 +242,6 @@ void __init snp_fixup_e820_tables(void)
 	}
 }
 
-static bool __init clear_rmptable_bookkeeping(void)
-{
-	void *bk;
-
-	bk = memremap(probed_rmp_base, RMPTABLE_CPU_BOOKKEEPING_SZ, MEMREMAP_WB);
-	if (!bk) {
-		pr_err("Failed to map RMP bookkeeping area\n");
-		return false;
-	}
-
-	memset(bk, 0, RMPTABLE_CPU_BOOKKEEPING_SZ);
-
-	memunmap(bk);
-
-	return true;
-}
-
 static bool __init alloc_rmp_segment_desc(u64 segment_pa, u64 segment_size, u64 pa)
 {
 	u64 rst_index, rmp_segment_size_max;
@@ -474,10 +459,22 @@ e_free:
 static bool __init setup_rmptable(void)
 {
 	if (rmp_cfg & MSR_AMD64_SEG_RMP_ENABLED) {
-		return setup_segmented_rmptable();
+		if (!setup_segmented_rmptable())
+			return false;
 	} else {
-		return setup_contiguous_rmptable();
+		if (!setup_contiguous_rmptable())
+			return false;
 	}
+
+	rmp_bookkeeping = memremap(probed_rmp_base, RMPTABLE_CPU_BOOKKEEPING_SZ, MEMREMAP_WB);
+	if (!rmp_bookkeeping) {
+		pr_err("Failed to map RMP bookkeeping area\n");
+		free_rmp_segment_table();
+
+		return false;
+	}
+
+	return true;
 }
 
 /*
@@ -508,10 +505,7 @@ int __init snp_rmptable_init(void)
 		goto skip_enable;
 
 	/* Zero out the RMP bookkeeping area */
-	if (!clear_rmptable_bookkeeping()) {
-		free_rmp_segment_table();
-		return -ENOSYS;
-	}
+	memset(rmp_bookkeeping, 0, RMPTABLE_CPU_BOOKKEEPING_SZ);
 
 	/* Zero out the RMP entries */
 	for (i = 0; i < rst_max_index; i++) {