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authorWei Huang <wei@redhat.com>2019-03-29 15:12:53 -0500
committerMarc Zyngier <marc.zyngier@arm.com>2019-03-30 10:06:00 +0000
commit8fa76162487143d202db20ce84e12061b671a058 (patch)
tree09aa11fc53786a4e0079683f16752899f4fd875b
parent8324c3d518cfd69f2a17866b52c13bf56d3042d8 (diff)
KVM: arm/arm64: arch_timer: Fix CNTP_TVAL calculation
Recently the generic timer test of kvm-unit-tests failed to complete (stalled) when a physical timer is being used. This issue is caused by incorrect update of CNTP_CVAL when CNTP_TVAL is being accessed, introduced by 'Commit 84135d3d18da ("KVM: arm/arm64: consolidate arch timer trap handlers")'. According to Arm ARM, the read/write behavior of accesses to the TVAL registers is expected to be: * READ: TimerValue = (CompareValue – (Counter - Offset) * WRITE: CompareValue = ((Counter - Offset) + Sign(TimerValue) This patch fixes the TVAL read/write code path according to the specification. Fixes: 84135d3d18da ("KVM: arm/arm64: consolidate arch timer trap handlers") Signed-off-by: Wei Huang <wei@redhat.com> [maz: commit message tidy-up] Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
-rw-r--r--virt/kvm/arm/arch_timer.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
index 3417f2dbc366..d43308dc3617 100644
--- a/virt/kvm/arm/arch_timer.c
+++ b/virt/kvm/arm/arch_timer.c
@@ -812,7 +812,7 @@ static u64 kvm_arm_timer_read(struct kvm_vcpu *vcpu,
switch (treg) {
case TIMER_REG_TVAL:
- val = kvm_phys_timer_read() - timer->cntvoff - timer->cnt_cval;
+ val = timer->cnt_cval - kvm_phys_timer_read() + timer->cntvoff;
break;
case TIMER_REG_CTL:
@@ -858,7 +858,7 @@ static void kvm_arm_timer_write(struct kvm_vcpu *vcpu,
{
switch (treg) {
case TIMER_REG_TVAL:
- timer->cnt_cval = val - kvm_phys_timer_read() - timer->cntvoff;
+ timer->cnt_cval = kvm_phys_timer_read() - timer->cntvoff + val;
break;
case TIMER_REG_CTL: