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

1 files changed, 17 insertions, 23 deletions

diff --git a/arch/x86/virt/svm/sev.c b/arch/x86/virt/svm/sev.c
index 5e07f103c271..e35fac0a8a3d 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++) {