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i386/kvm: add support for Direct Mode for Hyper-V synthetic timers

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Hyper-V on KVM can only use Synthetic timers with Direct Mode (opting for
an interrupt instead of VMBus message). This new capability is only
announced in KVM_GET_SUPPORTED_HV_CPUID.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20190517141924.19024-10-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Vitaly Kuznetsov 2019-05-17 16:19:24 +02:00 committed by Paolo Bonzini
parent 8caba36db5
commit 128531d9e1
5 changed files with 23 additions and 0 deletions
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10
docs/hyperv.txt
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@ -174,6 +174,16 @@ without the feature to find out if enabling it is beneficial.
Requires: hv-vapic
3.17. hv-stimer-direct
=======================
Hyper-V specification allows synthetic timer operation in two modes: "classic",
when expiration event is delivered as SynIC message and "direct", when the event
is delivered via normal interrupt. It is known that nested Hyper-V can only
use synthetic timers in direct mode and thus 'hv-stimer-direct' needs to be
enabled.
Requires: hv-vpindex, hv-synic, hv-time, hv-stimer
4. Development features
========================

2
target/i386/cpu.c
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@ -5883,6 +5883,8 @@ static Property x86_cpu_properties[] = {
HYPERV_FEAT_EVMCS, 0),
DEFINE_PROP_BIT64("hv-ipi", X86CPU, hyperv_features,
HYPERV_FEAT_IPI, 0),
DEFINE_PROP_BIT64("hv-stimer-direct", X86CPU, hyperv_features,
HYPERV_FEAT_STIMER_DIRECT, 0),
DEFINE_PROP_BOOL("hv-passthrough", X86CPU, hyperv_passthrough, false),
DEFINE_PROP_BOOL("check", X86CPU, check_cpuid, true),

1
target/i386/cpu.h
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@ -749,6 +749,7 @@ typedef uint32_t FeatureWordArray[FEATURE_WORDS];
#define HYPERV_FEAT_TLBFLUSH 11
#define HYPERV_FEAT_EVMCS 12
#define HYPERV_FEAT_IPI 13
#define HYPERV_FEAT_STIMER_DIRECT 14
#ifndef HYPERV_SPINLOCK_NEVER_RETRY
#define HYPERV_SPINLOCK_NEVER_RETRY 0xFFFFFFFF

1
target/i386/hyperv-proto.h
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@ -49,6 +49,7 @@
#define HV_GUEST_IDLE_STATE_AVAILABLE (1u << 5)
#define HV_FREQUENCY_MSRS_AVAILABLE (1u << 8)
#define HV_GUEST_CRASH_MSR_AVAILABLE (1u << 10)
#define HV_STIMER_DIRECT_MODE_AVAILABLE (1u << 19)
/*
* HV_CPUID_ENLIGHTMENT_INFO.EAX bits

9
target/i386/kvm.c
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@ -802,6 +802,14 @@ static struct {
},
.dependencies = BIT(HYPERV_FEAT_VPINDEX)
},
[HYPERV_FEAT_STIMER_DIRECT] = {
.desc = "direct mode synthetic timers (hv-stimer-direct)",
.flags = {
{.fw = FEAT_HYPERV_EDX,
.bits = HV_STIMER_DIRECT_MODE_AVAILABLE}
},
.dependencies = BIT(HYPERV_FEAT_STIMER)
},
};
static struct kvm_cpuid2 *try_get_hv_cpuid(CPUState *cs, int max)
@ -1124,6 +1132,7 @@ static int hyperv_handle_properties(CPUState *cs,
r |= hv_cpuid_check_and_set(cs, cpuid, HYPERV_FEAT_TLBFLUSH);
r |= hv_cpuid_check_and_set(cs, cpuid, HYPERV_FEAT_EVMCS);
r |= hv_cpuid_check_and_set(cs, cpuid, HYPERV_FEAT_IPI);
r |= hv_cpuid_check_and_set(cs, cpuid, HYPERV_FEAT_STIMER_DIRECT);
/* Additional dependencies not covered by kvm_hyperv_properties[] */
if (hyperv_feat_enabled(cpu, HYPERV_FEAT_SYNIC) &&