On Tue, 2019-09-10 at 16:24 +0800, Xiaoyao Li wrote:
> When limit checking is required, it should be executed first, which is
> consistent with the CPUID specification.
>
> Signed-off-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
> ---
> arch/x86/kvm/cpuid.c | 50 +++++++++++++++++++++++++-------------------
> 1 file changed, 28 insertions(+), 22 deletions(-)
>
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 22c2720cd948..866546b4d834 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -952,23 +952,33 @@ struct kvm_cpuid_entry2 *kvm_find_cpuid_entry(struct
> kvm_vcpu *vcpu,
> EXPORT_SYMBOL_GPL(kvm_find_cpuid_entry);
>
> /*
> - * If no match is found, check whether we exceed the vCPU's limit
> - * and return the content of the highest valid _standard_ leaf instead.
> - * This is to satisfy the CPUID specification.
> + * Based on CPUID specification, if leaf number exceeds the vCPU's limit,
> + * it should return the content of the highest valid _standard_ leaf instead.
> + * Note: *found is set true only means the queried leaf number doesn't exceed
> + * the maximum leaf number of basic or extented leaf.
> */
> -static struct kvm_cpuid_entry2* check_cpuid_limit(struct kvm_vcpu *vcpu,
> - u32 function, u32 index)
> +static struct kvm_cpuid_entry2* cpuid_check_limit(struct kvm_vcpu *vcpu,
> + u32 function, u32 index,
> + bool *found)
> {
> struct kvm_cpuid_entry2 *maxlevel;
>
> maxlevel = kvm_find_cpuid_entry(vcpu, function & 0x80000000, 0);
> - if (!maxlevel || maxlevel->eax >= function)
> + if (!maxlevel)
> return NULL;
> - if (function & 0x80000000) {
> - maxlevel = kvm_find_cpuid_entry(vcpu, 0, 0);
> - if (!maxlevel)
> - return NULL;
> +
> + if (maxlevel->eax >= function) {
> + if (found)
> + *found = true;
> + return kvm_find_cpuid_entry(vcpu, function, index);
> }
> +
> + if (function & 0x80000000)
> + maxlevel = kvm_find_cpuid_entry(vcpu, 0, 0);
> +
> + if (!maxlevel)
> + return NULL;
> +
> return kvm_find_cpuid_entry(vcpu, maxlevel->eax, index);
> }
>
> @@ -977,26 +987,22 @@ bool kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32
> *ebx,
> {
> u32 function = *eax, index = *ecx;
> struct kvm_cpuid_entry2 *best;
> - bool entry_found = true;
> + bool entry_found = false;
>
> - best = kvm_find_cpuid_entry(vcpu, function, index);
> + if (check_limit)
> + best = cpuid_check_limit(vcpu, function, index, &entry_found);
> + else
> + best = kvm_find_cpuid_entry(vcpu, function, index);
>
> - if (!best) {
> - entry_found = false;
> - if (!check_limit)
> - goto out;
> -
> - best = check_cpuid_limit(vcpu, function, index);
> - }
> -
> -out:
> if (best) {
> *eax = best->eax;
> *ebx = best->ebx;
> *ecx = best->ecx;
> *edx = best->edx;
> - } else
> + } else {
> + entry_found = false;
> *eax = *ebx = *ecx = *edx = 0;
> + }
> trace_kvm_cpuid(function, *eax, *ebx, *ecx, *edx, entry_found);
> return entry_found;
> }
Just realise the entry_found is not set true if found in no limit checking case.
Will send v2.
