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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen master] xen/arm: remove physical timer offset
commit f14f55b7ee295277c8dd09e37e0fa0902ccf7eb4
Author: Jeff Kubascik <jeff.kubascik@xxxxxxxxxxxxxxx>
AuthorDate: Tue Jan 21 10:07:03 2020 -0500
Commit: Julien Grall <julien@xxxxxxx>
CommitDate: Mon Jan 27 11:54:29 2020 +0000
xen/arm: remove physical timer offset
The physical timer traps apply an offset so that time starts at 0 for
the guest. However, this offset is not currently applied to the physical
counter. Per the ARMv8 Reference Manual (ARM DDI 0487E.a), section
D11.2.4 Timers, the "Offset" between the counter and timer should be
zero for a physical timer. This removes the offset to make the timer and
counter consistent.
This also cleans up the physical timer implementation to better match
the virtual timer - both cval's now hold the hardware value.
In the case the guest sets cval to a time before Xen started, the correct
behavior is to expire the timer immediately. To do this, we set the expires
argument of set_timer to zero.
Signed-off-by: Jeff Kubascik <jeff.kubascik@xxxxxxxxxxxxxxx>
Acked-by: Julien Grall <julien@xxxxxxx>
---
xen/arch/arm/vtimer.c | 46 +++++++++++++++++++++++++++++---------------
xen/include/asm-arm/domain.h | 3 ---
2 files changed, 30 insertions(+), 19 deletions(-)
diff --git a/xen/arch/arm/vtimer.c b/xen/arch/arm/vtimer.c
index 240a850b6e..08411f33a9 100644
--- a/xen/arch/arm/vtimer.c
+++ b/xen/arch/arm/vtimer.c
@@ -62,7 +62,6 @@ static void virt_timer_expired(void *data)
int domain_vtimer_init(struct domain *d, struct xen_arch_domainconfig *config)
{
- d->arch.phys_timer_base.offset = NOW();
d->arch.virt_timer_base.offset = READ_SYSREG64(CNTPCT_EL0);
d->time_offset.seconds = ticks_to_ns(d->arch.virt_timer_base.offset -
boot_count);
do_div(d->time_offset.seconds, 1000000000);
@@ -108,7 +107,6 @@ int vcpu_vtimer_init(struct vcpu *v)
init_timer(&t->timer, phys_timer_expired, t, v->processor);
t->ctl = 0;
- t->cval = NOW();
t->irq = d0
? timer_get_irq(TIMER_PHYS_NONSECURE_PPI)
: GUEST_TIMER_PHYS_NS_PPI;
@@ -167,6 +165,7 @@ void virt_timer_restore(struct vcpu *v)
static bool vtimer_cntp_ctl(struct cpu_user_regs *regs, uint32_t *r, bool read)
{
struct vcpu *v = current;
+ s_time_t expires;
if ( !ACCESS_ALLOWED(regs, EL0PTEN) )
return false;
@@ -184,8 +183,13 @@ static bool vtimer_cntp_ctl(struct cpu_user_regs *regs,
uint32_t *r, bool read)
if ( v->arch.phys_timer.ctl & CNTx_CTL_ENABLE )
{
- set_timer(&v->arch.phys_timer.timer,
- v->arch.phys_timer.cval +
v->domain->arch.phys_timer_base.offset);
+ /*
+ * If cval is before the point Xen started, expire timer
+ * immediately.
+ */
+ expires = v->arch.phys_timer.cval > boot_count
+ ? ticks_to_ns(v->arch.phys_timer.cval - boot_count) : 0;
+ set_timer(&v->arch.phys_timer.timer, expires);
}
else
stop_timer(&v->arch.phys_timer.timer);
@@ -197,26 +201,31 @@ static bool vtimer_cntp_tval(struct cpu_user_regs *regs,
uint32_t *r,
bool read)
{
struct vcpu *v = current;
- s_time_t now;
+ uint64_t cntpct;
+ s_time_t expires;
if ( !ACCESS_ALLOWED(regs, EL0PTEN) )
return false;
- now = NOW() - v->domain->arch.phys_timer_base.offset;
+ cntpct = get_cycles();
if ( read )
{
- *r = (uint32_t)(ns_to_ticks(v->arch.phys_timer.cval - now) &
0xffffffffull);
+ *r = (uint32_t)((v->arch.phys_timer.cval - cntpct) & 0xffffffffull);
}
else
{
- v->arch.phys_timer.cval = now + ticks_to_ns(*r);
+ v->arch.phys_timer.cval = cntpct + *r;
if ( v->arch.phys_timer.ctl & CNTx_CTL_ENABLE )
{
v->arch.phys_timer.ctl &= ~CNTx_CTL_PENDING;
- set_timer(&v->arch.phys_timer.timer,
- v->arch.phys_timer.cval +
- v->domain->arch.phys_timer_base.offset);
+ /*
+ * If cval is before the point Xen started, expire timer
+ * immediately.
+ */
+ expires = v->arch.phys_timer.cval > boot_count
+ ? ticks_to_ns(v->arch.phys_timer.cval - boot_count) : 0;
+ set_timer(&v->arch.phys_timer.timer, expires);
}
}
return true;
@@ -226,23 +235,28 @@ static bool vtimer_cntp_cval(struct cpu_user_regs *regs,
uint64_t *r,
bool read)
{
struct vcpu *v = current;
+ s_time_t expires;
if ( !ACCESS_ALLOWED(regs, EL0PTEN) )
return false;
if ( read )
{
- *r = ns_to_ticks(v->arch.phys_timer.cval);
+ *r = v->arch.phys_timer.cval;
}
else
{
- v->arch.phys_timer.cval = ticks_to_ns(*r);
+ v->arch.phys_timer.cval = *r;
if ( v->arch.phys_timer.ctl & CNTx_CTL_ENABLE )
{
v->arch.phys_timer.ctl &= ~CNTx_CTL_PENDING;
- set_timer(&v->arch.phys_timer.timer,
- v->arch.phys_timer.cval +
- v->domain->arch.phys_timer_base.offset);
+ /*
+ * If cval is before the point Xen started, expire timer
+ * immediately.
+ */
+ expires = v->arch.phys_timer.cval > boot_count
+ ? ticks_to_ns(v->arch.phys_timer.cval - boot_count) : 0;
+ set_timer(&v->arch.phys_timer.timer, expires);
}
}
return true;
diff --git a/xen/include/asm-arm/domain.h b/xen/include/asm-arm/domain.h
index f3f3fb7d7f..adc7fe7210 100644
--- a/xen/include/asm-arm/domain.h
+++ b/xen/include/asm-arm/domain.h
@@ -67,9 +67,6 @@ struct arch_domain
struct {
uint64_t offset;
- } phys_timer_base;
- struct {
- uint64_t offset;
} virt_timer_base;
struct vgic_dist vgic;
--
generated by git-patchbot for /home/xen/git/xen.git#master
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