| Message ID | 20211229131328.12283-4-yang.zhong@intel.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | AMX Support in KVM | expand |
On Wed, Dec 29, 2021, Yang Zhong wrote: > From: Jing Liu <jing2.liu@intel.com> > > CPUID.0xD.1.EBX enumerates the size of the XSAVE area (in compacted > format) required by XSAVES. If CPUID.0xD.i.ECX[1] is set for a state > component (i), this state component should be located on the next > 64-bytes boundary following the preceding state component in the > compacted layout. > > Fix xstate_required_size() to follow the alignment rule. AMX is the > first state component with 64-bytes alignment to catch this bug. > > Signed-off-by: Jing Liu <jing2.liu@intel.com> > Signed-off-by: Yang Zhong <yang.zhong@intel.com> > --- > arch/x86/kvm/cpuid.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > index 07e9215e911d..148003e26cbb 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -42,7 +42,8 @@ static u32 xstate_required_size(u64 xstate_bv, bool compacted) > if (xstate_bv & 0x1) { > u32 eax, ebx, ecx, edx, offset; > cpuid_count(0xD, feature_bit, &eax, &ebx, &ecx, &edx); > - offset = compacted ? ret : ebx; > + /* ECX[1]: 64B alignment in compacted form */ > + offset = compacted ? ((ecx & 0x2) ? ALIGN(ret, 64) : ret) : ebx; That is impressively difficult to read. if (compacted) offset = (ecx & 0x2) ? ALIGN(ret, 64) : ret; else offset = ebx; > ret = max(ret, offset + eax); > } >
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 07e9215e911d..148003e26cbb 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -42,7 +42,8 @@ static u32 xstate_required_size(u64 xstate_bv, bool compacted) if (xstate_bv & 0x1) { u32 eax, ebx, ecx, edx, offset; cpuid_count(0xD, feature_bit, &eax, &ebx, &ecx, &edx); - offset = compacted ? ret : ebx; + /* ECX[1]: 64B alignment in compacted form */ + offset = compacted ? ((ecx & 0x2) ? ALIGN(ret, 64) : ret) : ebx; ret = max(ret, offset + eax); }