[v2] Add AMD Secure Nested Paging (SEV-SNP) Initialization Support

[PATCH v2 05/25] x86/mtrr: Don't print errors if MtrrFixDramModEn is set when SNP enabled

Posted by Michael Roth 1 year, 11 months ago

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

SNP enabled platforms require the MtrrFixDramModeEn bit to be set across
all CPUs when SNP is enabled. Therefore, don't print error messages when
MtrrFixDramModeEn is set when bringing CPUs online.

Reported-by: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
Closes: https://lore.kernel.org/kvm/68b2d6bf-bce7-47f9-bebb-2652cc923ff9@linux.microsoft.com/
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
Signed-off-by: Michael Roth <michael.roth@amd.com>
---
 arch/x86/kernel/cpu/mtrr/generic.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c
index d3524778a545..422a4ddc2ab7 100644
--- a/arch/x86/kernel/cpu/mtrr/generic.c
+++ b/arch/x86/kernel/cpu/mtrr/generic.c
@@ -108,6 +108,9 @@ static inline void k8_check_syscfg_dram_mod_en(void)
 	      (boot_cpu_data.x86 >= 0x0f)))
 		return;
 
+	if (cpu_feature_enabled(X86_FEATURE_SEV_SNP))
+		return;
+
 	rdmsr(MSR_AMD64_SYSCFG, lo, hi);
 	if (lo & K8_MTRRFIXRANGE_DRAM_MODIFY) {
 		pr_err(FW_WARN "MTRR: CPU %u: SYSCFG[MtrrFixDramModEn]"
-- 
2.25.1

[tip: x86/sev] x86/mtrr: Don't print errors if MtrrFixDramModEn is set when SNP enabled

Posted by tip-bot2 for Ashish Kalra 1 year, 10 months ago

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

Commit-ID:     e3fd08afb7c350d5612f113eadfb4ebb6ed08deb
Gitweb:        https://git.kernel.org/tip/e3fd08afb7c350d5612f113eadfb4ebb6ed08deb
Author:        Ashish Kalra <ashish.kalra@amd.com>
AuthorDate:    Thu, 25 Jan 2024 22:11:05 -06:00
Committer:     Borislav Petkov (AMD) <bp@alien8.de>
CommitterDate: Mon, 29 Jan 2024 17:24:27 +01:00

x86/mtrr: Don't print errors if MtrrFixDramModEn is set when SNP enabled

SNP enabled platforms require the MtrrFixDramModeEn bit to be set across
all CPUs when SNP is enabled. Therefore, don't print error messages when
MtrrFixDramModeEn is set when bringing CPUs online.

Closes: https://lore.kernel.org/kvm/68b2d6bf-bce7-47f9-bebb-2652cc923ff9@linux.microsoft.com/
Reported-by: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
Signed-off-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20240126041126.1927228-6-michael.roth@amd.com
---
 arch/x86/kernel/cpu/mtrr/generic.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c
index d352477..422a4dd 100644
--- a/arch/x86/kernel/cpu/mtrr/generic.c
+++ b/arch/x86/kernel/cpu/mtrr/generic.c
@@ -108,6 +108,9 @@ static inline void k8_check_syscfg_dram_mod_en(void)
 	      (boot_cpu_data.x86 >= 0x0f)))
 		return;
 
+	if (cpu_feature_enabled(X86_FEATURE_SEV_SNP))
+		return;
+
 	rdmsr(MSR_AMD64_SYSCFG, lo, hi);
 	if (lo & K8_MTRRFIXRANGE_DRAM_MODIFY) {
 		pr_err(FW_WARN "MTRR: CPU %u: SYSCFG[MtrrFixDramModEn]"