From 8fa76162487143d202db20ce84e12061b671a058 Mon Sep 17 00:00:00 2001 From: Wei Huang Date: Fri, 29 Mar 2019 15:12:53 -0500 Subject: KVM: arm/arm64: arch_timer: Fix CNTP_TVAL calculation MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 [maz: commit message tidy-up] Signed-off-by: Marc Zyngier --- virt/kvm/arm/arch_timer.c | 4 ++-- 1 file 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: -- cgit