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KVM: x86: Use gfn_to_pfn_cache for pv_time

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Add a new kvm_setup_guest_pvclock() which parallels the existing
kvm_setup_pvclock_page(). The latter will be removed once we convert
all users to the gfn_to_pfn_cache version.

Using the new cache, we can potentially let kvm_set_guest_paused() set
the PVCLOCK_GUEST_STOPPED bit directly rather than having to delegate
to the vCPU via KVM_REQ_CLOCK_UPDATE. But not yet.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220303154127.202856-5-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
David Woodhouse 2022-03-03 15:41:14 +00:00 committed by Paolo Bonzini
parent a795cd43c5
commit 916d3608df
2 changed files with 64 additions and 15 deletions
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3
arch/x86/include/asm/kvm_host.h
View File

@ -751,8 +751,7 @@ struct kvm_vcpu_arch {
gpa_t time;
struct pvclock_vcpu_time_info hv_clock;
unsigned int hw_tsc_khz;
struct gfn_to_hva_cache pv_time;
bool pv_time_enabled;
struct gfn_to_pfn_cache pv_time;
/* set guest stopped flag in pvclock flags field */
bool pvclock_set_guest_stopped_request;

76
arch/x86/kvm/x86.c
View File

@ -2249,14 +2249,13 @@ static void kvm_write_system_time(struct kvm_vcpu *vcpu, gpa_t system_time,
kvm_make_request(KVM_REQ_GLOBAL_CLOCK_UPDATE, vcpu);
/* we verify if the enable bit is set... */
vcpu->arch.pv_time_enabled = false;
if (!(system_time & 1))
return;
if (!kvm_gfn_to_hva_cache_init(vcpu->kvm,
&vcpu->arch.pv_time, system_time & ~1ULL,
sizeof(struct pvclock_vcpu_time_info)))
vcpu->arch.pv_time_enabled = true;
if (system_time & 1) {
kvm_gfn_to_pfn_cache_init(vcpu->kvm, &vcpu->arch.pv_time, vcpu,
KVM_HOST_USES_PFN, system_time & ~1ULL,
sizeof(struct pvclock_vcpu_time_info));
} else {
kvm_gfn_to_pfn_cache_destroy(vcpu->kvm, &vcpu->arch.pv_time);
}
return;
}
@ -2961,6 +2960,57 @@ u64 get_kvmclock_ns(struct kvm *kvm)
return data.clock;
}
static void kvm_setup_guest_pvclock(struct kvm_vcpu *v,
struct gfn_to_pfn_cache *gpc,
unsigned int offset)
{
struct kvm_vcpu_arch *vcpu = &v->arch;
struct pvclock_vcpu_time_info *guest_hv_clock;
unsigned long flags;
read_lock_irqsave(&gpc->lock, flags);
while (!kvm_gfn_to_pfn_cache_check(v->kvm, gpc, gpc->gpa,
offset + sizeof(*guest_hv_clock))) {
read_unlock_irqrestore(&gpc->lock, flags);
if (kvm_gfn_to_pfn_cache_refresh(v->kvm, gpc, gpc->gpa,
offset + sizeof(*guest_hv_clock)))
return;
read_lock_irqsave(&gpc->lock, flags);
}
guest_hv_clock = (void *)(gpc->khva + offset);
/*
* This VCPU is paused, but it's legal for a guest to read another
* VCPU's kvmclock, so we really have to follow the specification where
* it says that version is odd if data is being modified, and even after
* it is consistent.
*/
guest_hv_clock->version = vcpu->hv_clock.version = (guest_hv_clock->version + 1) | 1;
smp_wmb();
/* retain PVCLOCK_GUEST_STOPPED if set in guest copy */
vcpu->hv_clock.flags |= (guest_hv_clock->flags & PVCLOCK_GUEST_STOPPED);
if (vcpu->pvclock_set_guest_stopped_request) {
vcpu->hv_clock.flags |= PVCLOCK_GUEST_STOPPED;
vcpu->pvclock_set_guest_stopped_request = false;
}
memcpy(guest_hv_clock, &vcpu->hv_clock, sizeof(*guest_hv_clock));
smp_wmb();
guest_hv_clock->version = ++vcpu->hv_clock.version;
mark_page_dirty_in_slot(v->kvm, gpc->memslot, gpc->gpa >> PAGE_SHIFT);
read_unlock_irqrestore(&gpc->lock, flags);
trace_kvm_pvclock_update(v->vcpu_id, &vcpu->hv_clock);
}
static void kvm_setup_pvclock_page(struct kvm_vcpu *v,
struct gfn_to_hva_cache *cache,
unsigned int offset)
@ -3106,8 +3156,8 @@ static int kvm_guest_time_update(struct kvm_vcpu *v)
vcpu->hv_clock.flags = pvclock_flags;
if (vcpu->pv_time_enabled)
kvm_setup_pvclock_page(v, &vcpu->pv_time, 0);
if (vcpu->pv_time.active)
kvm_setup_guest_pvclock(v, &vcpu->pv_time, 0);
if (vcpu->xen.vcpu_info_set)
kvm_setup_pvclock_page(v, &vcpu->xen.vcpu_info_cache,
offsetof(struct compat_vcpu_info, time));
@ -3301,7 +3351,7 @@ static int kvm_pv_enable_async_pf_int(struct kvm_vcpu *vcpu, u64 data)
static void kvmclock_reset(struct kvm_vcpu *vcpu)
{
vcpu->arch.pv_time_enabled = false;
kvm_gfn_to_pfn_cache_destroy(vcpu->kvm, &vcpu->arch.pv_time);
vcpu->arch.time = 0;
}
@ -5103,7 +5153,7 @@ static int kvm_vcpu_ioctl_x86_set_xcrs(struct kvm_vcpu *vcpu,
*/
static int kvm_set_guest_paused(struct kvm_vcpu *vcpu)
{
if (!vcpu->arch.pv_time_enabled)
if (!vcpu->arch.pv_time.active)
return -EINVAL;
vcpu->arch.pvclock_set_guest_stopped_request = true;
kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
@ -6187,7 +6237,7 @@ static int kvm_arch_suspend_notifier(struct kvm *kvm)
mutex_lock(&kvm->lock);
kvm_for_each_vcpu(i, vcpu, kvm) {
if (!vcpu->arch.pv_time_enabled)
if (!vcpu->arch.pv_time.active)
continue;
ret = kvm_set_guest_paused(vcpu);