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

Paolo Bonzini
2019-04-18T16:36:58Z

On 18/04/19 16:19, Borislav Petkov wrote:
> 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?

No need, squashing this in before running away for vacation.

Paolo