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SubjectRe: [PATCH 6/6] KVM: x86: Add requested index to the CPUID tracepoint
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On 02.03.20 20:57, Sean Christopherson wrote:
> Output the requested index when tracing CPUID emulation; it's basically
> mandatory for leafs where the index is meaningful, and is helpful for
> verifying KVM correctness even when the index isn't meaningful, e.g. the
> trace for a Linux guest's hypervisor_cpuid_base() probing appears to
> be broken (returns all zeroes) at first glance, but is correct because
> the index is non-zero, i.e. the output values correspond to random index
> in the maximum basic leaf.
>
> Suggested-by: Xiaoyao Li <xiaoyao.li@intel.com>
> Cc: Jan Kiszka <jan.kiszka@siemens.com>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> ---
> arch/x86/kvm/cpuid.c | 3 ++-
> arch/x86/kvm/trace.h | 13 ++++++++-----
> 2 files changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index b0a4f3c17932..a3c9f6bf43f3 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -1047,7 +1047,8 @@ void kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32 *ebx,
> }
> }
> }
> - trace_kvm_cpuid(function, *eax, *ebx, *ecx, *edx, exact_entry_exists);
> + trace_kvm_cpuid(function, index, *eax, *ebx, *ecx, *edx,
> + exact_entry_exists);
> }
> EXPORT_SYMBOL_GPL(kvm_cpuid);
>
> diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
> index f194dd058470..aa372d0119f0 100644
> --- a/arch/x86/kvm/trace.h
> +++ b/arch/x86/kvm/trace.h
> @@ -151,12 +151,14 @@ TRACE_EVENT(kvm_fast_mmio,
> * Tracepoint for cpuid.
> */
> TRACE_EVENT(kvm_cpuid,
> - TP_PROTO(unsigned int function, unsigned long rax, unsigned long rbx,
> - unsigned long rcx, unsigned long rdx, bool found),
> - TP_ARGS(function, rax, rbx, rcx, rdx, found),
> + TP_PROTO(unsigned int function, unsigned int index, unsigned long rax,
> + unsigned long rbx, unsigned long rcx, unsigned long rdx,
> + bool found),
> + TP_ARGS(function, index, rax, rbx, rcx, rdx, found),
>
> TP_STRUCT__entry(
> __field( unsigned int, function )
> + __field( unsigned int, index )
> __field( unsigned long, rax )
> __field( unsigned long, rbx )
> __field( unsigned long, rcx )
> @@ -166,6 +168,7 @@ TRACE_EVENT(kvm_cpuid,
>
> TP_fast_assign(
> __entry->function = function;
> + __entry->index = index;
> __entry->rax = rax;
> __entry->rbx = rbx;
> __entry->rcx = rcx;
> @@ -173,8 +176,8 @@ TRACE_EVENT(kvm_cpuid,
> __entry->found = found;
> ),
>
> - TP_printk("func %x rax %lx rbx %lx rcx %lx rdx %lx, cpuid entry %s",
> - __entry->function, __entry->rax,
> + TP_printk("func %x idx %x rax %lx rbx %lx rcx %lx rdx %lx, cpuid entry %s",
> + __entry->function, __entry->index, __entry->rax,
> __entry->rbx, __entry->rcx, __entry->rdx,
> __entry->found ? "found" : "not found")
> );
>

What happened to this patch in your v2 round?

Jan

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