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authorVitaly Kuznetsov <vkuznets@redhat.com>2021-08-10 23:52:46 +0300
committerPaolo Bonzini <pbonzini@redhat.com>2021-08-20 16:06:25 -0400
commit0f250a646382e017725001a552624be0c86527bf (patch)
treea75ce6127efc2b6bff57e7d031c696f47a63c5b8 /arch/x86/kvm/hyperv.c
parent4628efcd4e8963a41e877318cd10346dea9a6e00 (diff)
KVM: x86: hyper-v: Deactivate APICv only when AutoEOI feature is in use
APICV_INHIBIT_REASON_HYPERV is currently unconditionally forced upon SynIC activation as SynIC's AutoEOI is incompatible with APICv/AVIC. It is, however, possible to track whether the feature was actually used by the guest and only inhibit APICv/AVIC when needed. TLFS suggests a dedicated 'HV_DEPRECATING_AEOI_RECOMMENDED' flag to let Windows know that AutoEOI feature should be avoided. While it's up to KVM userspace to set the flag, KVM can help a bit by exposing global APICv/AVIC enablement. Maxim: - always set HV_DEPRECATING_AEOI_RECOMMENDED in kvm_get_hv_cpuid, since this feature can be used regardless of AVIC Paolo: - use arch.apicv_update_lock to protect the hv->synic_auto_eoi_used instead of atomic ops Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> Message-Id: <20210810205251.424103-12-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/hyperv.c')
-rw-r--r--arch/x86/kvm/hyperv.c32
1 files changed, 26 insertions, 6 deletions
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 0b38f944c6b6..fe4a02715266 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -88,6 +88,10 @@ static bool synic_has_vector_auto_eoi(struct kvm_vcpu_hv_synic *synic,
static void synic_update_vector(struct kvm_vcpu_hv_synic *synic,
int vector)
{
+ struct kvm_vcpu *vcpu = hv_synic_to_vcpu(synic);
+ struct kvm_hv *hv = to_kvm_hv(vcpu->kvm);
+ int auto_eoi_old, auto_eoi_new;
+
if (vector < HV_SYNIC_FIRST_VALID_VECTOR)
return;
@@ -96,10 +100,30 @@ static void synic_update_vector(struct kvm_vcpu_hv_synic *synic,
else
__clear_bit(vector, synic->vec_bitmap);
+ auto_eoi_old = bitmap_weight(synic->auto_eoi_bitmap, 256);
+
if (synic_has_vector_auto_eoi(synic, vector))
__set_bit(vector, synic->auto_eoi_bitmap);
else
__clear_bit(vector, synic->auto_eoi_bitmap);
+
+ auto_eoi_new = bitmap_weight(synic->auto_eoi_bitmap, 256);
+
+ if (!!auto_eoi_old == !!auto_eoi_new)
+ return;
+
+ mutex_lock(&vcpu->kvm->arch.apicv_update_lock);
+
+ if (auto_eoi_new)
+ hv->synic_auto_eoi_used++;
+ else
+ hv->synic_auto_eoi_used--;
+
+ __kvm_request_apicv_update(vcpu->kvm,
+ !hv->synic_auto_eoi_used,
+ APICV_INHIBIT_REASON_HYPERV);
+
+ mutex_unlock(&vcpu->kvm->arch.apicv_update_lock);
}
static int synic_set_sint(struct kvm_vcpu_hv_synic *synic, int sint,
@@ -933,12 +957,6 @@ int kvm_hv_activate_synic(struct kvm_vcpu *vcpu, bool dont_zero_synic_pages)
synic = to_hv_synic(vcpu);
- /*
- * Hyper-V SynIC auto EOI SINT's are
- * not compatible with APICV, so request
- * to deactivate APICV permanently.
- */
- kvm_request_apicv_update(vcpu->kvm, false, APICV_INHIBIT_REASON_HYPERV);
synic->active = true;
synic->dont_zero_synic_pages = dont_zero_synic_pages;
synic->control = HV_SYNIC_CONTROL_ENABLE;
@@ -2476,6 +2494,8 @@ int kvm_get_hv_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid,
ent->eax |= HV_X64_ENLIGHTENED_VMCS_RECOMMENDED;
if (!cpu_smt_possible())
ent->eax |= HV_X64_NO_NONARCH_CORESHARING;
+
+ ent->eax |= HV_DEPRECATING_AEOI_RECOMMENDED;
/*
* Default number of spinlock retry attempts, matches
* HyperV 2016.