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 --- Documentation/virtual/kvm/msr.txt | 9 +++++++++ arch/x86/include/asm/kvm_host.h | 2 ++ arch/x86/include/uapi/asm/kvm_para.h | 2 ++ arch/x86/kvm/Kconfig | 1 + arch/x86/kvm/cpuid.c | 3 ++- arch/x86/kvm/x86.c | 23 +++++++++++++++++++++++ 6 files changed, 39 insertions(+), 1 deletion(-) Index: linux-2.6.git/Documentation/virtual/kvm/msr.txt =================================================================== --- linux-2.6.git.orig/Documentation/virtual/kvm/msr.txt 2018-05-18 15:40:19.697438928 -0300 +++ linux-2.6.git/Documentation/virtual/kvm/msr.txt 2019-06-03 19:37:49.618543527 -0300 @@ -273,3 +273,12 @@ 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 halt poll + logic. + KVM guests can disable host halt polling when performing + polling themselves. + Index: linux-2.6.git/arch/x86/include/asm/kvm_host.h =================================================================== --- linux-2.6.git.orig/arch/x86/include/asm/kvm_host.h 2019-05-29 14:46:14.516005546 -0300 +++ linux-2.6.git/arch/x86/include/asm/kvm_host.h 2019-06-03 19:37:49.619543530 -0300 @@ -755,6 +755,8 @@ 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 Index: linux-2.6.git/arch/x86/include/uapi/asm/kvm_para.h =================================================================== --- linux-2.6.git.orig/arch/x86/include/uapi/asm/kvm_para.h 2019-01-04 12:07:15.936947406 -0200 +++ linux-2.6.git/arch/x86/include/uapi/asm/kvm_para.h 2019-06-03 19:37:49.620543534 -0300 @@ -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; Index: linux-2.6.git/arch/x86/kvm/Kconfig =================================================================== --- linux-2.6.git.orig/arch/x86/kvm/Kconfig 2019-05-29 14:46:14.530005593 -0300 +++ linux-2.6.git/arch/x86/kvm/Kconfig 2019-06-03 19:37:49.620543534 -0300 @@ -41,6 +41,7 @@ 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 Index: linux-2.6.git/arch/x86/kvm/cpuid.c =================================================================== --- linux-2.6.git.orig/arch/x86/kvm/cpuid.c 2019-05-29 14:46:14.530005593 -0300 +++ linux-2.6.git/arch/x86/kvm/cpuid.c 2019-06-03 19:37:49.621543537 -0300 @@ -643,7 +643,8 @@ (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); Index: linux-2.6.git/arch/x86/kvm/x86.c =================================================================== --- linux-2.6.git.orig/arch/x86/kvm/x86.c 2019-05-29 14:46:14.537005616 -0300 +++ linux-2.6.git/arch/x86/kvm/x86.c 2019-06-03 19:37:49.624543547 -0300 @@ -1177,6 +1177,7 @@ MSR_IA32_POWER_CTL, MSR_K7_HWCR, + MSR_KVM_POLL_CONTROL, }; static unsigned num_emulated_msrs; @@ -2628,6 +2629,14 @@ 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: @@ -2877,6 +2886,9 @@ 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: @@ -8874,6 +8886,10 @@ 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) @@ -9948,6 +9964,13 @@ } 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);