Re: [Qemu-devel] [PATCH RESEND v2] i386/kvm: add support for KVM_CAP_X86_DISABLE_EXITS

[Wanpeng Li]

2018-05-12 5:57 GMT+08:00 Michael S. Tsirkin <address@hidden>:
> On Wed, Apr 18, 2018 at 09:09:19AM +0800, Wanpeng Li wrote:
>> 2018-04-18 2:08 GMT+08:00 Michael S. Tsirkin <address@hidden>:
>> > On Tue, Apr 17, 2018 at 01:24:15AM -0700, Wanpeng Li wrote:
>> >> From: Wanpeng Li <address@hidden>
>> >>
>> >> This patch adds support for KVM_CAP_X86_DISABLE_EXITS. Provides userspace 
>> >> with
>> >> per-VM capability(KVM_CAP_X86_DISABLE_EXITS) to not intercept 
>> >> MWAIT/HLT/PAUSE
>> >> in order that to improve latency in some workloads.
>> >>
>> >> Cc: Paolo Bonzini <address@hidden>
>> >> Cc: Radim Krčmář <address@hidden>
>> >> Cc: Eduardo Habkost <address@hidden>
>> >> Signed-off-by: Wanpeng Li <address@hidden>
>> >> ---
>> >>
>> >>  linux-headers/linux/kvm.h |  6 +++++-
>> >>  target/i386/cpu.h         |  2 ++
>> >>  target/i386/kvm.c         | 16 ++++++++++++++++
>> >>  3 files changed, 23 insertions(+), 1 deletion(-)
>> >>
>> >> diff --git a/linux-headers/linux/kvm.h b/linux-headers/linux/kvm.h
>> >> index a167be8..857df15 100644
>> >> --- a/linux-headers/linux/kvm.h
>> >> +++ b/linux-headers/linux/kvm.h
>> >> @@ -925,7 +925,7 @@ struct kvm_ppc_resize_hpt {
>> >>  #define KVM_CAP_S390_GS 140
>> >>  #define KVM_CAP_S390_AIS 141
>> >>  #define KVM_CAP_SPAPR_TCE_VFIO 142
>> >> -#define KVM_CAP_X86_GUEST_MWAIT 143
>> >> +#define KVM_CAP_X86_DISABLE_EXITS 143
>> >>  #define KVM_CAP_ARM_USER_IRQ 144
>> >>  #define KVM_CAP_S390_CMMA_MIGRATION 145
>> >>  #define KVM_CAP_PPC_FWNMI 146
>> >> @@ -1508,6 +1508,10 @@ struct kvm_assigned_msix_entry {
>> >>  #define KVM_X2APIC_API_USE_32BIT_IDS            (1ULL << 0)
>> >>  #define KVM_X2APIC_API_DISABLE_BROADCAST_QUIRK  (1ULL << 1)
>> >>
>> >> +#define KVM_X86_DISABLE_EXITS_MWAIT          (1 << 0)
>> >> +#define KVM_X86_DISABLE_EXITS_HLT            (1 << 1)
>> >> +#define KVM_X86_DISABLE_EXITS_PAUSE          (1 << 2)
>> >> +
>> >>  /* Available with KVM_CAP_ARM_USER_IRQ */
>> >>
>> >>  /* Bits for run->s.regs.device_irq_level */
>> >> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
>> >> index 1b219fa..965de1b 100644
>> >> --- a/target/i386/cpu.h
>> >> +++ b/target/i386/cpu.h
>> >> @@ -685,6 +685,8 @@ typedef uint32_t FeatureWordArray[FEATURE_WORDS];
>> >>  #define CPUID_7_0_EDX_AVX512_4FMAPS (1U << 3) /* AVX512 Multiply 
>> >> Accumulation Single Precision */
>> >>  #define CPUID_7_0_EDX_SPEC_CTRL     (1U << 26) /* Speculation Control */
>> >>
>> >> +#define KVM_PV_UNHALT (1U << 7)
>> >> +
>> >
>> > Why don't we use KVM_FEATURE_PV_UNHALT from kvm_para.h?
>> >
>> >>  #define KVM_HINTS_DEDICATED (1U << 0)
>> >>
>> >
>> > BTW I wonder whether we should switch to a value from
>> > kvm_para.h? I'll send a version to do it, pls take a look.
>>
>> Yeah, your patchset looks good.
>>
>> Regards,
>> Wanpeng Li
>
> Do you plan to rebase your patch and upstream it or do you expect me to
> do it?

You can pick it since I am too busy recently. Thanks Michael!

Regards,
Wanpeng Li