From: Wei Huang <wei@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: wei@redhat.com, julien.thierry@arm.com, marc.zyngier@arm.com,
andre.przywara@arm.com, suzuki.poulose@arm.com,
christoffer.dall@arm.com, james.morse@arm.com,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/1] KVM: arm/arm64: arch_timer: Fix TimerValue TVAL calculation in KVM
Date: Fri, 29 Mar 2019 15:12:53 -0500 [thread overview]
Message-ID: <20190329201253.29164-1-wei@redhat.com> (raw)
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 CNT_CVAL when TimerValue 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 TimeValue 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.
Signed-off-by: Wei Huang <wei@redhat.com>
---
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:
--
2.14.5
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next reply other threads:[~2019-03-29 20:13 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-29 20:12 Wei Huang [this message]
2019-03-30 9:56 ` [PATCH 1/1] KVM: arm/arm64: arch_timer: Fix TimerValue TVAL calculation in KVM Marc Zyngier
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190329201253.29164-1-wei@redhat.com \
--to=wei@redhat.com \
--cc=andre.przywara@arm.com \
--cc=christoffer.dall@arm.com \
--cc=james.morse@arm.com \
--cc=julien.thierry@arm.com \
--cc=kvmarm@lists.cs.columbia.edu \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=marc.zyngier@arm.com \
--cc=suzuki.poulose@arm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).