On Fri, Apr 26, 2019 at 11:44:46PM +0800, Like Xu wrote: > Add support to expose Intel V2 Extended Topology Enumeration Leaf for > some new systems with multiple software-visible die within each package. > > When CPUID executes with EAX set to 1FH, the processor returns information > about extended topology enumeration data. Software must detect the presence > of CPUID leaf 1FH by verifying (a) the highest leaf index supported by > CPUID is >= 1FH, and (b) CPUID.1FH:EBX[15:0] reports a non-zero value. Nit: When quoting the SDM, it's helpful to explicitly say so, otherwise readers may assume you're just stating your take on things. Reviewed-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx> > > Co-developed-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxxxxxxxx> > Signed-off-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxxxxxxxx> > Signed-off-by: Like Xu <like.xu@xxxxxxxxxxxxxxx> > --- > > ==changelog== > v3: > - Redefine commit message and comment > > v2: > - Apply cpuid.1f check rule on Intel SDM page 3-222 Vol.2A > - Add comment to handle 0x1f anf 0xb in common code > - Reduce check time in a descending-break style > > v1: https://lkml.org/lkml/2019/4/22/28 > > arch/x86/kvm/cpuid.c | 11 ++++++++++- > 1 file changed, 10 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > index fd39516..176a67a 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -425,6 +425,11 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function, > > switch (function) { > case 0: > + /* Check if the cpuid leaf 0x1f is actually implemented */ > + if (entry->eax >= 0x1f && (cpuid_ebx(0x1f) & 0x0000ffff)) { > + entry->eax = 0x1f; > + break; > + } > entry->eax = min(entry->eax, (u32)(f_intel_pt ? 0x14 : 0xd)); > break; > case 1: > @@ -544,7 +549,11 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function, > entry->edx = edx.full; > break; > } > - /* function 0xb has additional index. */ > + /* > + * Per Intel's SDM, 0x1f is a superset of 0xb, thus they can be handled > + * by common code. > + */ > + case 0x1f: > case 0xb: { > int i, level_type; > > -- > 1.8.3.1 >
