x86, msr: Add rd/wrmsr interfaces with preset registers

native_{rdmsr,wrmsr}_safe_regs are two new interfaces which allow
presetting of a subset of eight x86 GPRs before executing the rd/wrmsr
instructions. This is needed at least on AMD K8 for accessing an erratum
workaround MSR.

Originally based on an idea by H. Peter Anvin.

Signed-off-by: Borislav Petkov <petkovbb@gmail.com>
LKML-Reference: <1251705011-18636-1-git-send-email-petkovbb@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index 70ec9b951d76..67594af43b38 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -362,8 +362,10 @@ struct pv_cpu_ops pv_cpu_ops = {
 #endif
         .wbinvd = native_wbinvd,
         .read_msr = native_read_msr_safe,
+        .rdmsr_regs = native_rdmsr_safe_regs,
         .read_msr_amd = native_read_msr_amd_safe,
         .write_msr = native_write_msr_safe,
+        .wrmsr_regs = native_wrmsr_safe_regs,
         .read_tsc = native_read_tsc,
         .read_pmc = native_read_pmc,
         .read_tscp = native_read_tscp,