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SubjectRe: [PATCH v6 2/8] KVM: x86: Add a helper function for CPUID(0xD,n>=1) enumeration
On Mon, Aug 12, 2019 at 03:18:11PM -0700, Sean Christopherson wrote:
> On Thu, Jul 25, 2019 at 11:12:40AM +0800, Yang Weijiang wrote:
> > To make the code look clean, wrap CPUID(0xD,n>=1) enumeration
> > code in a helper function now.
> >
> > Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
> > ---
> > arch/x86/kvm/cpuid.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
> > 1 file changed, 44 insertions(+)
> >
> > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> > index 4992e7c99588..29cbde7538a3 100644
> > --- a/arch/x86/kvm/cpuid.c
> > +++ b/arch/x86/kvm/cpuid.c
> > @@ -313,6 +313,50 @@ static int __do_cpuid_ent_emulated(struct kvm_cpuid_entry2 *entry,
> > return 0;
> > }
> >
> > +static inline int __do_cpuid_dx_leaf(struct kvm_cpuid_entry2 *entry, int *nent,
>
> 'dx' makes me think of the generic reference to RDX vs EDX. Maybe
> __do_cpuid_0xd_leaf()?
>
OK, will change it.
> > + int maxnent, u64 xss_mask, u64 xcr0_mask,
> > + u32 eax_mask)
> > +{
> > + int idx, i;
> > + u64 mask;
> > + u64 supported;
> > +
> > + for (idx = 1, i = 1; idx < 64; ++idx) {
>
> Rather than loop here, I think it makes sense to loop in the caller to
> make the code consistent with do_cpuid_7_mask() added by commit
>
> 54d360d41211 ("KVM: cpuid: extract do_cpuid_7_mask and support multiple subleafs")
>
OK, will follow the patch to modify the helper.

> > + mask = ((u64)1 << idx);
> > + if (*nent >= maxnent)
> > + return -EINVAL;
> > +
> > + do_cpuid_1_ent(&entry[i], 0xD, idx);
> > + if (idx == 1) {
> > + entry[i].eax &= eax_mask;
> > + cpuid_mask(&entry[i].eax, CPUID_D_1_EAX);
> > + supported = xcr0_mask | xss_mask;
> > + entry[i].ebx = 0;
> > + entry[i].edx = 0;
> > + entry[i].ecx &= xss_mask;
> > + if (entry[i].eax & (F(XSAVES) | F(XSAVEC))) {
> > + entry[i].ebx =
> > + xstate_required_size(supported,
> > + true);
> > + }
> > + } else {
> > + supported = (entry[i].ecx & 1) ? xss_mask :
> > + xcr0_mask;
> > + if (entry[i].eax == 0 || !(supported & mask))
> > + continue;
> > + entry[i].ecx &= 1;
> > + entry[i].edx = 0;
> > + if (entry[i].ecx)
> > + entry[i].ebx = 0;
> > + }
> > + entry[i].flags |=
> > + KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
> > + ++*nent;
> > + ++i;
> > + }
> > + return 0;
> > +}
> > +
>
> Extracting code into a helper should be done in the same patch that the
> existing code is replaced with a call to the helper, i.e. the chunk of the
> next patch that invokes the helper should be squashed with this patch.
>
OK, will squash this patch in next release.

> > static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
> > u32 index, int *nent, int maxnent)
> > {
> > --
> > 2.17.2
> >

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