From: David Woodhouse <dwmw@xxxxxxxxxxxx>
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@xxxxxxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 3 +-
arch/x86/kvm/x86.c | 76 +++++++++++++++++++++++++++------
2 files changed, 64 insertions(+), 15 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index a04616569805..127cef57f50b 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -746,8 +746,7 @@ 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;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b1c65771c31d..43c1a431537a 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2229,14 +2229,13 @@ 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;
}
@@ -2939,6 +2938,57 @@ 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)
@@ -3084,8 +3134,8 @@ 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));
@@ -3279,7 +3329,7 @@ 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;
}
@@ -5079,7 +5129,7 @@ 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);
@@ -6158,7 +6208,7 @@ 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);
--
2.33.1
