From efc479e6900c22bad9a2b649d13405ed9cde2d53 Mon Sep 17 00:00:00 2001 From: Roman Kagan Date: Thu, 22 Jun 2017 16:51:01 +0300 Subject: kvm: x86: hyperv: add KVM_CAP_HYPERV_SYNIC2 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit There is a flaw in the Hyper-V SynIC implementation in KVM: when message page or event flags page is enabled by setting the corresponding msr, KVM zeroes it out. This is problematic because on migration the corresponding MSRs are loaded on the destination, so the content of those pages is lost. This went unnoticed so far because the only user of those pages was in-KVM hyperv synic timers, which could continue working despite that zeroing. Newer QEMU uses those pages for Hyper-V VMBus implementation, and zeroing them breaks the migration. Besides, in newer QEMU the content of those pages is fully managed by QEMU, so zeroing them is undesirable even when writing the MSRs from the guest side. To support this new scheme, introduce a new capability, KVM_CAP_HYPERV_SYNIC2, which, when enabled, makes sure that the synic pages aren't zeroed out in KVM. Signed-off-by: Roman Kagan Signed-off-by: Radim Krčmář --- arch/x86/kvm/hyperv.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/x86/kvm/hyperv.h') diff --git a/arch/x86/kvm/hyperv.h b/arch/x86/kvm/hyperv.h index cd1119538add..12f65fe1011d 100644 --- a/arch/x86/kvm/hyperv.h +++ b/arch/x86/kvm/hyperv.h @@ -56,7 +56,7 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu); void kvm_hv_irq_routing_update(struct kvm *kvm); int kvm_hv_synic_set_irq(struct kvm *kvm, u32 vcpu_id, u32 sint); void kvm_hv_synic_send_eoi(struct kvm_vcpu *vcpu, int vector); -int kvm_hv_activate_synic(struct kvm_vcpu *vcpu); +int kvm_hv_activate_synic(struct kvm_vcpu *vcpu, bool dont_zero_synic_pages); void kvm_hv_vcpu_init(struct kvm_vcpu *vcpu); void kvm_hv_vcpu_uninit(struct kvm_vcpu *vcpu); -- cgit v1.2.3 From d3457c877b14aaee8c52923eedf05a3b78af0476 Mon Sep 17 00:00:00 2001 From: Roman Kagan Date: Fri, 14 Jul 2017 17:13:20 +0300 Subject: kvm: x86: hyperv: make VP_INDEX managed by userspace MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Hyper-V identifies vCPUs by Virtual Processor Index, which can be queried via HV_X64_MSR_VP_INDEX msr. It is defined by the spec as a sequential number which can't exceed the maximum number of vCPUs per VM. APIC ids can be sparse and thus aren't a valid replacement for VP indices. Current KVM uses its internal vcpu index as VP_INDEX. However, to make it predictable and persistent across VM migrations, the userspace has to control the value of VP_INDEX. This patch achieves that, by storing vp_index explicitly on vcpu, and allowing HV_X64_MSR_VP_INDEX to be set from the host side. For compatibility it's initialized to KVM vcpu index. Also a few variables are renamed to make clear distinction betweed this Hyper-V vp_index and KVM vcpu_id (== APIC id). Besides, a new capability, KVM_CAP_HYPERV_VP_INDEX, is added to allow the userspace to skip attempting msr writes where unsupported, to avoid spamming error logs. Signed-off-by: Roman Kagan Signed-off-by: Radim Krčmář --- Documentation/virtual/kvm/api.txt | 9 +++++++ arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/hyperv.c | 54 +++++++++++++++++++++++++-------------- arch/x86/kvm/hyperv.h | 1 + arch/x86/kvm/x86.c | 3 +++ include/uapi/linux/kvm.h | 1 + 6 files changed, 50 insertions(+), 19 deletions(-) (limited to 'arch/x86/kvm/hyperv.h') diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index 78ac577c9378..e63a35fafef0 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -4338,3 +4338,12 @@ This capability enables a newer version of Hyper-V Synthetic interrupt controller (SynIC). The only difference with KVM_CAP_HYPERV_SYNIC is that KVM doesn't clear SynIC message and event flags pages when they are enabled by writing to the respective MSRs. + +8.12 KVM_CAP_HYPERV_VP_INDEX + +Architectures: x86 + +This capability indicates that userspace can load HV_X64_MSR_VP_INDEX msr. Its +value is used to denote the target vcpu for a SynIC interrupt. For +compatibilty, KVM initializes this msr to KVM's internal vcpu index. When this +capability is absent, userspace can still query this msr's value. diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index da3261e384d3..87ac4fba6d8e 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -467,6 +467,7 @@ struct kvm_vcpu_hv_synic { /* Hyper-V per vcpu emulation context */ struct kvm_vcpu_hv { + u32 vp_index; u64 hv_vapic; s64 runtime_offset; struct kvm_vcpu_hv_synic synic; diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c index a8084406707e..2695a34fa1c5 100644 --- a/arch/x86/kvm/hyperv.c +++ b/arch/x86/kvm/hyperv.c @@ -106,14 +106,27 @@ static int synic_set_sint(struct kvm_vcpu_hv_synic *synic, int sint, return 0; } -static struct kvm_vcpu_hv_synic *synic_get(struct kvm *kvm, u32 vcpu_id) +static struct kvm_vcpu *get_vcpu_by_vpidx(struct kvm *kvm, u32 vpidx) +{ + struct kvm_vcpu *vcpu = NULL; + int i; + + if (vpidx < KVM_MAX_VCPUS) + vcpu = kvm_get_vcpu(kvm, vpidx); + if (vcpu && vcpu_to_hv_vcpu(vcpu)->vp_index == vpidx) + return vcpu; + kvm_for_each_vcpu(i, vcpu, kvm) + if (vcpu_to_hv_vcpu(vcpu)->vp_index == vpidx) + return vcpu; + return NULL; +} + +static struct kvm_vcpu_hv_synic *synic_get(struct kvm *kvm, u32 vpidx) { struct kvm_vcpu *vcpu; struct kvm_vcpu_hv_synic *synic; - if (vcpu_id >= atomic_read(&kvm->online_vcpus)) - return NULL; - vcpu = kvm_get_vcpu(kvm, vcpu_id); + vcpu = get_vcpu_by_vpidx(kvm, vpidx); if (!vcpu) return NULL; synic = vcpu_to_synic(vcpu); @@ -320,11 +333,11 @@ static int synic_set_irq(struct kvm_vcpu_hv_synic *synic, u32 sint) return ret; } -int kvm_hv_synic_set_irq(struct kvm *kvm, u32 vcpu_id, u32 sint) +int kvm_hv_synic_set_irq(struct kvm *kvm, u32 vpidx, u32 sint) { struct kvm_vcpu_hv_synic *synic; - synic = synic_get(kvm, vcpu_id); + synic = synic_get(kvm, vpidx); if (!synic) return -EINVAL; @@ -343,11 +356,11 @@ void kvm_hv_synic_send_eoi(struct kvm_vcpu *vcpu, int vector) kvm_hv_notify_acked_sint(vcpu, i); } -static int kvm_hv_set_sint_gsi(struct kvm *kvm, u32 vcpu_id, u32 sint, int gsi) +static int kvm_hv_set_sint_gsi(struct kvm *kvm, u32 vpidx, u32 sint, int gsi) { struct kvm_vcpu_hv_synic *synic; - synic = synic_get(kvm, vcpu_id); + synic = synic_get(kvm, vpidx); if (!synic) return -EINVAL; @@ -689,6 +702,13 @@ void kvm_hv_vcpu_init(struct kvm_vcpu *vcpu) stimer_init(&hv_vcpu->stimer[i], i); } +void kvm_hv_vcpu_postcreate(struct kvm_vcpu *vcpu) +{ + struct kvm_vcpu_hv *hv_vcpu = vcpu_to_hv_vcpu(vcpu); + + hv_vcpu->vp_index = kvm_vcpu_get_idx(vcpu); +} + int kvm_hv_activate_synic(struct kvm_vcpu *vcpu, bool dont_zero_synic_pages) { struct kvm_vcpu_hv_synic *synic = vcpu_to_synic(vcpu); @@ -983,6 +1003,11 @@ static int kvm_hv_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data, bool host) struct kvm_vcpu_hv *hv = &vcpu->arch.hyperv; switch (msr) { + case HV_X64_MSR_VP_INDEX: + if (!host) + return 1; + hv->vp_index = (u32)data; + break; case HV_X64_MSR_APIC_ASSIST_PAGE: { u64 gfn; unsigned long addr; @@ -1094,18 +1119,9 @@ static int kvm_hv_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata) struct kvm_vcpu_hv *hv = &vcpu->arch.hyperv; switch (msr) { - case HV_X64_MSR_VP_INDEX: { - int r; - struct kvm_vcpu *v; - - kvm_for_each_vcpu(r, v, vcpu->kvm) { - if (v == vcpu) { - data = r; - break; - } - } + case HV_X64_MSR_VP_INDEX: + data = hv->vp_index; break; - } case HV_X64_MSR_EOI: return kvm_hv_vapic_msr_read(vcpu, APIC_EOI, pdata); case HV_X64_MSR_ICR: diff --git a/arch/x86/kvm/hyperv.h b/arch/x86/kvm/hyperv.h index 12f65fe1011d..e637631a9574 100644 --- a/arch/x86/kvm/hyperv.h +++ b/arch/x86/kvm/hyperv.h @@ -59,6 +59,7 @@ void kvm_hv_synic_send_eoi(struct kvm_vcpu *vcpu, int vector); int kvm_hv_activate_synic(struct kvm_vcpu *vcpu, bool dont_zero_synic_pages); void kvm_hv_vcpu_init(struct kvm_vcpu *vcpu); +void kvm_hv_vcpu_postcreate(struct kvm_vcpu *vcpu); void kvm_hv_vcpu_uninit(struct kvm_vcpu *vcpu); static inline struct kvm_vcpu_hv_stimer *vcpu_to_stimer(struct kvm_vcpu *vcpu, diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 6753f0982791..5b8f07889f6a 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2666,6 +2666,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) case KVM_CAP_HYPERV_SPIN: case KVM_CAP_HYPERV_SYNIC: case KVM_CAP_HYPERV_SYNIC2: + case KVM_CAP_HYPERV_VP_INDEX: case KVM_CAP_PCI_SEGMENT: case KVM_CAP_DEBUGREGS: case KVM_CAP_X86_ROBUST_SINGLESTEP: @@ -7688,6 +7689,8 @@ void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu) struct msr_data msr; struct kvm *kvm = vcpu->kvm; + kvm_hv_vcpu_postcreate(vcpu); + if (vcpu_load(vcpu)) return; msr.data = 0x0; diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 38b2cfbc8112..6cd63c18708a 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -928,6 +928,7 @@ struct kvm_ppc_resize_hpt { #define KVM_CAP_PPC_FWNMI 146 #define KVM_CAP_PPC_SMT_POSSIBLE 147 #define KVM_CAP_HYPERV_SYNIC2 148 +#define KVM_CAP_HYPERV_VP_INDEX 149 #ifdef KVM_CAP_IRQ_ROUTING -- cgit v1.2.3