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authorPaolo Bonzini <pbonzini@redhat.com>2023-03-14 09:40:39 -0400
committerPaolo Bonzini <pbonzini@redhat.com>2023-03-14 09:40:39 -0400
commitbceeedb2f0b803fa188b931b30c064ee60196f09 (patch)
tree527c70145cde7ed5b11cc41e8621244c225881df /arch
parenteeac8ede17557680855031c6f305ece2378af326 (diff)
parent47053904e18282af4525a02e3e0f519f014fc7f9 (diff)
Merge tag 'kvmarm-fixes-6.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD
KVM/arm64 fixes for 6.3, part #1 A single patch to address a rather annoying bug w.r.t. guest timer offsetting. Effectively the synchronization of timer offsets between vCPUs was broken, leading to inconsistent timer reads within the VM.
Diffstat (limited to 'arch')
-rw-r--r--arch/arm64/include/asm/kvm_host.h3
-rw-r--r--arch/arm64/kvm/arch_timer.c45
-rw-r--r--arch/arm64/kvm/hypercalls.c2
3 files changed, 14 insertions, 36 deletions
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index a1892a8f6032..bcd774d74f34 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -193,6 +193,9 @@ struct kvm_arch {
/* Interrupt controller */
struct vgic_dist vgic;
+ /* Timers */
+ struct arch_timer_vm_data timer_data;
+
/* Mandated version of PSCI */
u32 psci_version;
diff --git a/arch/arm64/kvm/arch_timer.c b/arch/arm64/kvm/arch_timer.c
index 00610477ec7b..e1af4301b913 100644
--- a/arch/arm64/kvm/arch_timer.c
+++ b/arch/arm64/kvm/arch_timer.c
@@ -84,14 +84,10 @@ u64 timer_get_cval(struct arch_timer_context *ctxt)
static u64 timer_get_offset(struct arch_timer_context *ctxt)
{
- struct kvm_vcpu *vcpu = ctxt->vcpu;
+ if (ctxt->offset.vm_offset)
+ return *ctxt->offset.vm_offset;
- switch(arch_timer_ctx_index(ctxt)) {
- case TIMER_VTIMER:
- return __vcpu_sys_reg(vcpu, CNTVOFF_EL2);
- default:
- return 0;
- }
+ return 0;
}
static void timer_set_ctl(struct arch_timer_context *ctxt, u32 ctl)
@@ -128,15 +124,12 @@ static void timer_set_cval(struct arch_timer_context *ctxt, u64 cval)
static void timer_set_offset(struct arch_timer_context *ctxt, u64 offset)
{
- struct kvm_vcpu *vcpu = ctxt->vcpu;
-
- switch(arch_timer_ctx_index(ctxt)) {
- case TIMER_VTIMER:
- __vcpu_sys_reg(vcpu, CNTVOFF_EL2) = offset;
- break;
- default:
+ if (!ctxt->offset.vm_offset) {
WARN(offset, "timer %ld\n", arch_timer_ctx_index(ctxt));
+ return;
}
+
+ WRITE_ONCE(*ctxt->offset.vm_offset, offset);
}
u64 kvm_phys_timer_read(void)
@@ -765,25 +758,6 @@ int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu)
return 0;
}
-/* Make the updates of cntvoff for all vtimer contexts atomic */
-static void update_vtimer_cntvoff(struct kvm_vcpu *vcpu, u64 cntvoff)
-{
- unsigned long i;
- struct kvm *kvm = vcpu->kvm;
- struct kvm_vcpu *tmp;
-
- mutex_lock(&kvm->lock);
- kvm_for_each_vcpu(i, tmp, kvm)
- timer_set_offset(vcpu_vtimer(tmp), cntvoff);
-
- /*
- * When called from the vcpu create path, the CPU being created is not
- * included in the loop above, so we just set it here as well.
- */
- timer_set_offset(vcpu_vtimer(vcpu), cntvoff);
- mutex_unlock(&kvm->lock);
-}
-
void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
{
struct arch_timer_cpu *timer = vcpu_timer(vcpu);
@@ -791,10 +765,11 @@ void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
vtimer->vcpu = vcpu;
+ vtimer->offset.vm_offset = &vcpu->kvm->arch.timer_data.voffset;
ptimer->vcpu = vcpu;
/* Synchronize cntvoff across all vtimers of a VM. */
- update_vtimer_cntvoff(vcpu, kvm_phys_timer_read());
+ timer_set_offset(vtimer, kvm_phys_timer_read());
timer_set_offset(ptimer, 0);
hrtimer_init(&timer->bg_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_HARD);
@@ -840,7 +815,7 @@ int kvm_arm_timer_set_reg(struct kvm_vcpu *vcpu, u64 regid, u64 value)
break;
case KVM_REG_ARM_TIMER_CNT:
timer = vcpu_vtimer(vcpu);
- update_vtimer_cntvoff(vcpu, kvm_phys_timer_read() - value);
+ timer_set_offset(timer, kvm_phys_timer_read() - value);
break;
case KVM_REG_ARM_TIMER_CVAL:
timer = vcpu_vtimer(vcpu);
diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
index 64c086c02c60..5da884e11337 100644
--- a/arch/arm64/kvm/hypercalls.c
+++ b/arch/arm64/kvm/hypercalls.c
@@ -44,7 +44,7 @@ static void kvm_ptp_get_time(struct kvm_vcpu *vcpu, u64 *val)
feature = smccc_get_arg1(vcpu);
switch (feature) {
case KVM_PTP_VIRT_COUNTER:
- cycles = systime_snapshot.cycles - vcpu_read_sys_reg(vcpu, CNTVOFF_EL2);
+ cycles = systime_snapshot.cycles - vcpu->kvm->arch.timer_data.voffset;
break;
case KVM_PTP_PHYS_COUNTER:
cycles = systime_snapshot.cycles;