Currently, when an msr is updated using kvm_set_shared_msr the masked bits are
zeroed. This behavior is currently valid since the only MSR with partial mask
is EFER, in which only SCE might be unmasked. However, using the
kvm_set_shared_msr for other purposes becomes impossible.
This patch keeps the masked bits unmodified while setting a shared msr.
Signed-off-by: Nadav Amit <namit@xxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/x86.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 5f5edb6..ee42410 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -236,6 +236,7 @@ void kvm_set_shared_msr(unsigned slot, u64 value, u64 mask)
if (((value ^ smsr->values[slot].curr) & mask) == 0)
return;
+ value = (smsr->values[slot].curr & ~mask) | (value & mask);
smsr->values[slot].curr = value;
wrmsrl(shared_msrs_global.msrs[slot], value);
if (!smsr->registered) {
--
1.9.1
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