On 15.03.23 23:18, Sean Christopherson wrote:
> On Wed, Feb 01, 2023, Mathias Krause wrote:
>> Make use of the kvm_read_cr{0,4}_bits() helper functions when we only
>> want to know the state of certain bits instead of the whole register.
>>
>> This not only makes the intend cleaner, it also avoids a VMREAD in case
>> the tested bits aren't guest owned.
>>
>> Signed-off-by: Mathias Krause <minipli@xxxxxxxxxxxxxx>
>> ---
>> arch/x86/kvm/pmu.c | 4 ++--
>> arch/x86/kvm/vmx/vmx.c | 4 ++--
>> 2 files changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
>> index d939d3b84e6f..d9922277df67 100644
>> --- a/arch/x86/kvm/pmu.c
>> +++ b/arch/x86/kvm/pmu.c
>> @@ -439,9 +439,9 @@ int kvm_pmu_rdpmc(struct kvm_vcpu *vcpu, unsigned idx, u64 *data)
>> if (!pmc)
>> return 1;
>>
>> - if (!(kvm_read_cr4(vcpu) & X86_CR4_PCE) &&
>> + if (!(kvm_read_cr4_bits(vcpu, X86_CR4_PCE)) &&
>
> Purely as an FYI, I proposed adding helpers to query single CR0/CR4 bits in a
> separate thread[*]. No need to do anything on your end, I'll plan on applying
> this patch first and will handle whatever conflicts arise.
>
> [*] https://lore.kernel.org/all/ZAuRec2NkC3+4jvD@xxxxxxxxxx
Unfortunately, not all users of kvm_read_cr*_bits() only want to read a
single bit. There are a very few that read bit masks -- but you're
probably fully aware of this.
Thanks,
Mathias
