[RFC PATCH v4 04/28] x86: Handle reduction in physical address size with SME

Tom Lendacky
2017-02-16T15:42:54Z

When System Memory Encryption (SME) is enabled, the physical address
space is reduced. Adjust the x86_phys_bits value to reflect this
reduction.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
---
arch/x86/kernel/cpu/common.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index b33bc06..358208d7 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -771,11 +771,15 @@ void get_cpu_cap(struct cpuinfo_x86 *c)
u64 msr;

/*
- * For SME, BIOS support is required. If BIOS has not
- * enabled SME don't advertise the feature.
+ * For SME, BIOS support is required. If BIOS has
+ * enabled SME adjust x86_phys_bits by the SME
+ * physical address space reduction value. If BIOS
+ * has not enabled SME don't advertise the feature.
*/
rdmsrl(MSR_K8_SYSCFG, msr);
- if (!(msr & MSR_K8_SYSCFG_MEM_ENCRYPT))
+ if (msr & MSR_K8_SYSCFG_MEM_ENCRYPT)
+ c->x86_phys_bits -= (ebx >> 6) & 0x3f;
+ else
eax &= ~0x01;
}

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: email@kvack.org