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Subject[PATCH v10 05/38] x86/CPU/AMD: Handle SME reduction in physical address size
Date
When System Memory Encryption (SME) is enabled, the physical address
space is reduced. Adjust the x86_phys_bits value to reflect this
reduction.

Reviewed-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
arch/x86/kernel/cpu/amd.c | 24 +++++++++++++-----------
1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 7f658d0..e41670e 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -614,21 +614,23 @@ static void early_init_amd(struct cpuinfo_x86 *c)
set_cpu_bug(c, X86_BUG_AMD_E400);

/*
- * BIOS support is required for SME. If BIOS has not enabled SME
- * then don't advertise the feature (set in scattered.c). Also,
- * since the SME support requires long mode, don't advertise the
- * feature under CONFIG_X86_32.
+ * BIOS support is required for SME. If BIOS has enabled SME then
+ * adjust x86_phys_bits by the SME physical address space reduction
+ * value. If BIOS has not enabled SME then don't advertise the
+ * feature (set in scattered.c). Also, since the SME support requires
+ * long mode, don't advertise the feature under CONFIG_X86_32.
*/
if (cpu_has(c, X86_FEATURE_SME)) {
- if (IS_ENABLED(CONFIG_X86_32)) {
- clear_cpu_cap(c, X86_FEATURE_SME);
- } else {
- u64 msr;
+ u64 msr;

- /* Check if SME is enabled */
- rdmsrl(MSR_K8_SYSCFG, msr);
- if (!(msr & MSR_K8_SYSCFG_MEM_ENCRYPT))
+ /* Check if SME is enabled */
+ rdmsrl(MSR_K8_SYSCFG, msr);
+ if (msr & MSR_K8_SYSCFG_MEM_ENCRYPT) {
+ c->x86_phys_bits -= (cpuid_ebx(0x8000001f) >> 6) & 0x3f;
+ if (IS_ENABLED(CONFIG_X86_32))
clear_cpu_cap(c, X86_FEATURE_SME);
+ } else {
+ clear_cpu_cap(c, X86_FEATURE_SME);
}
}
}
--
1.9.1
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