From: Marc Zyngier <maz@kernel.org>
To: kvmarm@lists.linux.dev, kvm@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Cc: James Morse <james.morse@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Oliver Upton <oliver.upton@linux.dev>,
Zenghui Yu <yuzenghui@huawei.com>,
Ricardo Koller <ricarkol@google.com>,
Simon Veith <sveith@amazon.de>,
dwmw2@infradead.org
Subject: [PATCH 05/16] KVM: arm64: timers: Convert per-vcpu virtual offset to a global value
Date: Thu, 16 Feb 2023 14:21:12 +0000 [thread overview]
Message-ID: <20230216142123.2638675-6-maz@kernel.org> (raw)
In-Reply-To: <20230216142123.2638675-1-maz@kernel.org>
Having a per-vcpu virtual offset is a pain. It needs to be synchronized
on each update, and expands badly to a setup where different timers can
have different offsets, or have composite offsets (as with NV).
So let's start by replacing the use of the CNTVOFF_EL2 shadow register
(which we want to reclaim for NV anyway), and make the virtual timer
carry a pointer to a VM-wide offset.
This simplifies the code significantly.
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
arch/arm64/include/asm/kvm_host.h | 3 +++
arch/arm64/kvm/arch_timer.c | 45 +++++++------------------------
arch/arm64/kvm/hypercalls.c | 2 +-
include/kvm/arm_arch_timer.h | 15 +++++++++++
4 files changed, 29 insertions(+), 36 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 2a8175f38439..3adac0c5e175 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_offsets offsets;
+
/* Mandated version of PSCI */
u32 psci_version;
diff --git a/arch/arm64/kvm/arch_timer.c b/arch/arm64/kvm/arch_timer.c
index 329a8444724f..1bb44f668608 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.offsets.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..169d629f97cb 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.offsets.voffset;
break;
case KVM_PTP_PHYS_COUNTER:
cycles = systime_snapshot.cycles;
diff --git a/include/kvm/arm_arch_timer.h b/include/kvm/arm_arch_timer.h
index 76174f4fb646..41fda6255174 100644
--- a/include/kvm/arm_arch_timer.h
+++ b/include/kvm/arm_arch_timer.h
@@ -23,6 +23,19 @@ enum kvm_arch_timer_regs {
TIMER_REG_CTL,
};
+struct arch_timer_offset {
+ /*
+ * If set, pointer to one of the offsets in the kvm's offset
+ * structure. If NULL, assume a zero offset.
+ */
+ u64 *vm_offset;
+};
+
+struct arch_timer_vm_offsets {
+ /* Offset applied to the virtual timer/counter */
+ u64 voffset;
+};
+
struct arch_timer_context {
struct kvm_vcpu *vcpu;
@@ -33,6 +46,8 @@ struct arch_timer_context {
struct hrtimer hrtimer;
u64 ns_frac;
+ /* Offset for this counter/timer */
+ struct arch_timer_offset offset;
/*
* We have multiple paths which can save/restore the timer state onto
* the hardware, so we need some way of keeping track of where the
--
2.34.1
next prev parent reply other threads:[~2023-02-16 14:21 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-16 14:21 [PATCH 00/16] KVM: arm64: Rework timer offsetting for fun and profit Marc Zyngier
2023-02-16 14:21 ` [PATCH 01/16] arm64: Add CNTPOFF_EL2 register definition Marc Zyngier
2023-02-16 14:21 ` [PATCH 02/16] arm64: Add HAS_ECV_CNTPOFF capability Marc Zyngier
2023-02-22 4:30 ` Reiji Watanabe
2023-02-22 10:47 ` Marc Zyngier
2023-02-16 14:21 ` [PATCH 03/16] kvm: arm64: Expose {un,}lock_all_vcpus() to the reset of KVM Marc Zyngier
2023-02-23 22:30 ` Colton Lewis
2023-02-16 14:21 ` [PATCH 04/16] KVM: arm64: timers: Use a per-vcpu, per-timer accumulator for fractional ns Marc Zyngier
2023-02-23 22:30 ` Colton Lewis
2023-02-16 14:21 ` Marc Zyngier [this message]
2023-02-22 6:15 ` [PATCH 05/16] KVM: arm64: timers: Convert per-vcpu virtual offset to a global value Reiji Watanabe
2023-02-22 10:54 ` Marc Zyngier
2023-02-16 14:21 ` [PATCH 06/16] KVM: arm64: timers: Use CNTPOFF_EL2 to offset the physical timer Marc Zyngier
2023-02-23 22:34 ` Colton Lewis
2023-02-24 8:59 ` Marc Zyngier
2023-02-16 14:21 ` [PATCH 07/16] KVM: arm64: timers: Allow physical offset without CNTPOFF_EL2 Marc Zyngier
2023-02-23 22:40 ` Colton Lewis
2023-02-24 10:54 ` Marc Zyngier
2023-02-16 14:21 ` [PATCH 08/16] KVM: arm64: timers: Allow userspace to set the counter offsets Marc Zyngier
2023-02-16 22:09 ` Oliver Upton
2023-02-17 10:17 ` Marc Zyngier
2023-02-17 22:11 ` Oliver Upton
2023-02-22 11:56 ` Marc Zyngier
2023-02-22 16:34 ` Oliver Upton
2023-02-23 18:25 ` Marc Zyngier
2023-03-08 7:46 ` Oliver Upton
2023-03-08 7:53 ` Oliver Upton
2023-03-09 8:29 ` Marc Zyngier
2023-03-09 8:25 ` Marc Zyngier
2023-02-23 22:41 ` Colton Lewis
2023-02-24 11:24 ` Marc Zyngier
2023-02-16 14:21 ` [PATCH 09/16] KVM: arm64: timers: Allow save/restoring of the physical timer Marc Zyngier
2023-02-16 14:21 ` [PATCH 10/16] KVM: arm64: timers: Rationalise per-vcpu timer init Marc Zyngier
2023-02-16 14:21 ` [PATCH 11/16] KVM: arm64: Document KVM_ARM_SET_CNT_OFFSETS and co Marc Zyngier
2023-02-16 14:21 ` [PATCH 12/16] KVM: arm64: nv: timers: Add a per-timer, per-vcpu offset Marc Zyngier
2023-02-24 20:07 ` Colton Lewis
2023-02-25 10:32 ` Marc Zyngier
2023-02-16 14:21 ` [PATCH 13/16] KVM: arm64: nv: timers: Support hyp timer emulation Marc Zyngier
2023-02-24 20:08 ` Colton Lewis
2023-02-25 10:34 ` Marc Zyngier
2023-02-16 14:21 ` [PATCH 14/16] KVM: arm64: selftests: Add physical timer registers to the sysreg list Marc Zyngier
2023-02-16 14:21 ` [PATCH 15/16] KVM: arm64: selftests: Augment existing timer test to handle variable offsets Marc Zyngier
2023-03-06 22:08 ` Colton Lewis
2023-03-09 9:01 ` Marc Zyngier
2023-03-10 19:26 ` Colton Lewis
2023-03-12 15:53 ` Marc Zyngier
2023-03-13 11:43 ` Marc Zyngier
2023-03-14 17:47 ` Colton Lewis
2023-03-14 18:18 ` Marc Zyngier
2023-02-16 14:21 ` [PATCH 16/16] KVM: arm64: selftests: Deal with spurious timer interrupts Marc Zyngier
2023-02-21 16:28 ` [PATCH 00/16] KVM: arm64: Rework timer offsetting for fun and profit Veith, Simon
2023-02-21 22:17 ` Marc Zyngier
2023-02-23 22:29 ` Colton Lewis
2023-02-24 8:45 ` Marc Zyngier
2023-02-24 20:07 ` Colton Lewis
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