lkml.org 
[lkml]   [2019]   [Apr]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH -v5.1] x86/kvm: Implement HWCR support
On Thu, Apr 18, 2019 at 04:19:49PM +0200, 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;

At that point it probably makes sense to rework the whole block as there
are existing issues in both the CTL and STATUS flows:

- Fault cases should return '1', not '-1'.

- host_initiated should be checked for the CTL case


My personal preference would be to combine the host_initiated and !data
checks for brevity, so something like:

if (msr_info->host_initiated || !data)
goto set_msr;

offset = msr - MSR_IA32_MC0_CTL;
if ((offset & 0x3) == 0 && (data | (1 << 10)) != ~(u64)0)
return 1;
if ((offset & 0x3) == 1 && !can_set_mci_status(vcpu))
return 1;

set_msr:

>
> set_msr:
> ...
>
>
> Anything else? Can I send v5.2 now?
>
> --
> Regards/Gruss,
> Boris.
>
> Good mailing practices for 400: avoid top-posting and trim the reply.

\
 
 \ /
  Last update: 2019-04-18 16:38    [W:0.051 / U:20.300 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site