Messages in this thread | | | Subject | Re: [PATCH v8 2/2] x86/mm: Don't disable PCID if the kernel is running on a hypervisor | From | Xi Ruoyao <> | Date | Thu, 18 Apr 2024 02:26:38 +0800 |
| |
On Wed, 2024-04-17 at 11:23 -0700, Sean Christopherson wrote: > On Wed, Apr 17, 2024, Dave Hansen wrote: > > On 4/17/24 10:22, Pawan Gupta wrote: > > > > > static const struct x86_cpu_id invlpg_miss_ids[] = { > > > > > + /* Only bare-metal is affected. PCIDs in guests are OK. */ > > > > > + { > > > > > + .vendor = X86_VENDOR_INTEL, > > > > > + .family = 6, > > > > > + .model = INTEL_FAM6_ANY, > > Just in case we go this route (I hope we don't), this should probably be: > > /* Only bare-metal is affected PCIDs in guests are OK. */ > { > .vendor = X86_VENDOR_ANY, > .feature = X86_FEATURE_HYPERVISOR, > .driver_data = 0, > }, > > to make it clear that the goal is to match only the feature. Matching Intel P6 > suffices because that's what the other entries in the array all check, but it > makes subtle, confusing code even more subtle and confusing.
Agreed.
/* snip */
> > > > > > Let's just do the X86_FEATURE_HYPERVISOR explicitly in the code instead > > of trying to cram it into the invlpg_miss_ids[] check. It's way easier > > to understand with an explicit code check. > > +1. And it doesn't rely on the HYPERVISOR entry being the first entry, which > is doubly evil.
So I'll go with the explicit checking in v9. I'll send it tomorrow.
-- Xi Ruoyao <xry111@xry111.site> School of Aerospace Science and Technology, Xidian University
| |