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kvm: x86: add host poll control msrs 

Add an MSRs which allows the guest to disable
host polling (specifically the cpuidle-haltpoll,
when performing polling in the guest, disables
host side polling).

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Marcelo Tosatti 2019-06-03 19:52:44 -03:00 committed by Paolo Bonzini
parent fdb28619a8
commit 2d5ba19bdf
6 changed files with 39 additions and 1 deletions
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9
Documentation/virtual/kvm/msr.txt
View File

@ -273,3 +273,12 @@ MSR_KVM_EOI_EN: 0x4b564d04
guest must both read the least significant bit in the memory area and
clear it using a single CPU instruction, such as test and clear, or
compare and exchange.
MSR_KVM_POLL_CONTROL: 0x4b564d05
Control host-side polling.
data: Bit 0 enables (1) or disables (0) host-side HLT polling logic.
KVM guests can request the host not to poll on HLT, for example if
they are performing polling themselves.

2
arch/x86/include/asm/kvm_host.h
View File

@ -755,6 +755,8 @@ struct kvm_vcpu_arch {
struct gfn_to_hva_cache data;
} pv_eoi;
u64 msr_kvm_poll_control;
/*
* Indicate whether the access faults on its page table in guest
* which is set when fix page fault and used to detect unhandeable

2
arch/x86/include/uapi/asm/kvm_para.h
View File

@ -29,6 +29,7 @@
#define KVM_FEATURE_PV_TLB_FLUSH 9
#define KVM_FEATURE_ASYNC_PF_VMEXIT 10
#define KVM_FEATURE_PV_SEND_IPI 11
#define KVM_FEATURE_POLL_CONTROL 12
#define KVM_HINTS_REALTIME 0
@ -47,6 +48,7 @@
#define MSR_KVM_ASYNC_PF_EN 0x4b564d02
#define MSR_KVM_STEAL_TIME 0x4b564d03
#define MSR_KVM_PV_EOI_EN 0x4b564d04
#define MSR_KVM_POLL_CONTROL 0x4b564d05
struct kvm_steal_time {
__u64 steal;

1
arch/x86/kvm/Kconfig
View File

@ -41,6 +41,7 @@ config KVM
select PERF_EVENTS
select HAVE_KVM_MSI
select HAVE_KVM_CPU_RELAX_INTERCEPT
select HAVE_KVM_NO_POLL
select KVM_GENERIC_DIRTYLOG_READ_PROTECT
select KVM_VFIO
select SRCU

3
arch/x86/kvm/cpuid.c
View File

@ -658,7 +658,8 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
(1 << KVM_FEATURE_PV_UNHALT) |
(1 << KVM_FEATURE_PV_TLB_FLUSH) |
(1 << KVM_FEATURE_ASYNC_PF_VMEXIT) |
(1 << KVM_FEATURE_PV_SEND_IPI);
(1 << KVM_FEATURE_PV_SEND_IPI) |
(1 << KVM_FEATURE_POLL_CONTROL);
if (sched_info_on())
entry->eax |= (1 << KVM_FEATURE_STEAL_TIME);

23
arch/x86/kvm/x86.c
View File

@ -1177,6 +1177,7 @@ static u32 emulated_msrs[] = {
MSR_IA32_POWER_CTL,
MSR_K7_HWCR,
MSR_KVM_POLL_CONTROL,
};
static unsigned num_emulated_msrs;
@ -2636,6 +2637,14 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
return 1;
break;
case MSR_KVM_POLL_CONTROL:
/* only enable bit supported */
if (data & (-1ULL << 1))
return 1;
vcpu->arch.msr_kvm_poll_control = data;
break;
case MSR_IA32_MCG_CTL:
case MSR_IA32_MCG_STATUS:
case MSR_IA32_MC0_CTL ... MSR_IA32_MCx_CTL(KVM_MAX_MCE_BANKS) - 1:
@ -2885,6 +2894,9 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
case MSR_KVM_PV_EOI_EN:
msr_info->data = vcpu->arch.pv_eoi.msr_val;
break;
case MSR_KVM_POLL_CONTROL:
msr_info->data = vcpu->arch.msr_kvm_poll_control;
break;
case MSR_IA32_P5_MC_ADDR:
case MSR_IA32_P5_MC_TYPE:
case MSR_IA32_MCG_CAP:
@ -8861,6 +8873,10 @@ void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
msr.host_initiated = true;
kvm_write_tsc(vcpu, &msr);
vcpu_put(vcpu);
/* poll control enabled by default */
vcpu->arch.msr_kvm_poll_control = 1;
mutex_unlock(&vcpu->mutex);
if (!kvmclock_periodic_sync)
@ -9972,6 +9988,13 @@ bool kvm_vector_hashing_enabled(void)
}
EXPORT_SYMBOL_GPL(kvm_vector_hashing_enabled);
bool kvm_arch_no_poll(struct kvm_vcpu *vcpu)
{
return (vcpu->arch.msr_kvm_poll_control & 1) == 0;
}
EXPORT_SYMBOL_GPL(kvm_arch_no_poll);
EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_exit);
EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_fast_mmio);
EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_inj_virq);