Re: [PATCH -v5.1] x86/kvm: Implement HWCR support

Borislav Petkov
2019-04-18T14:19:58Z

On Thu, Apr 18, 2019 at 06:56:06AM -0700, Sean Christopherson wrote:
> This doesn't allow writing '0' regardless of msr_hwcr.BIT(18), which was
> previously supported.

Restored the old conditional:

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 10f6acc6494c..f74f1280745b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2318,7 +2318,8 @@ static int set_msr_mce(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
return -1;

/* MCi_STATUS */
- if ((offset & 0x3) == 1 && !msr_info->host_initiated) {
+ if (!msr_info->host_initiated &&
+ (offset & 0x3) == 1 && data != 0) {
if (!can_set_mci_status(vcpu))
return -1;
}

> And there's no need for multiple if statements.

It is a bit more readable this way.

Actually, I'd break that if above into smaller if-statements with
flipped logic to make it even more readable:

if (msr_info->host_initiated)
goto set_msr;

if (!(offset & 0x3))
goto set_msr;

if (!data)
goto set_msr;

if (!can_set_mci_status(vcpu))
return -1;

set_msr:
...

Anything else? Can I send v5.2 now?

--
Regards/Gruss,
Boris.

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