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KVM: arm64: timers: Use CNTPOFF_EL2 to offset the physical timer 

With ECV and CNTPOFF_EL2, it is very easy to offer an offset for
the physical timer. So let's do just that.

Nothing can set the offset yet, so this should have no effect
whatsoever (famous last words...).

Reviewed-by: Colton Lewis <coltonlewis@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230330174800.2677007-5-maz@kernel.org
This commit is contained in:
Marc Zyngier 2023-03-30 18:47:44 +01:00
parent 326349943e
commit 2b4825a869
4 changed files with 21 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
arch/arm64/kvm/arch_timer.c
View File

@ -52,6 +52,11 @@ static u64 kvm_arm_timer_read(struct kvm_vcpu *vcpu,
struct arch_timer_context *timer,
enum kvm_arch_timer_regs treg);
static bool has_cntpoff(void)
{
return (has_vhe() && cpus_have_final_cap(ARM64_HAS_ECV_CNTPOFF));
}
u32 timer_get_ctl(struct arch_timer_context *ctxt)
{
struct kvm_vcpu *vcpu = ctxt->vcpu;
@ -84,7 +89,7 @@ u64 timer_get_cval(struct arch_timer_context *ctxt)
static u64 timer_get_offset(struct arch_timer_context *ctxt)
{
if (ctxt->offset.vm_offset)
if (ctxt && ctxt->offset.vm_offset)
return *ctxt->offset.vm_offset;
return 0;
@ -432,6 +437,12 @@ static void set_cntvoff(u64 cntvoff)
kvm_call_hyp(__kvm_timer_set_cntvoff, cntvoff);
}
static void set_cntpoff(u64 cntpoff)
{
if (has_cntpoff())
write_sysreg_s(cntpoff, SYS_CNTPOFF_EL2);
}
static void timer_save_state(struct arch_timer_context *ctx)
{
struct arch_timer_cpu *timer = vcpu_timer(ctx->vcpu);
@ -480,6 +491,7 @@ static void timer_save_state(struct arch_timer_context *ctx)
write_sysreg_el0(0, SYS_CNTP_CTL);
isb();
set_cntpoff(0);
break;
case NR_KVM_TIMERS:
BUG();
@ -550,6 +562,7 @@ static void timer_restore_state(struct arch_timer_context *ctx)
write_sysreg_el0(timer_get_ctl(ctx), SYS_CNTV_CTL);
break;
case TIMER_PTIMER:
set_cntpoff(timer_get_offset(ctx));
write_sysreg_el0(timer_get_cval(ctx), SYS_CNTP_CVAL);
isb();
write_sysreg_el0(timer_get_ctl(ctx), SYS_CNTP_CTL);
@ -767,6 +780,7 @@ void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
vtimer->vcpu = vcpu;
vtimer->offset.vm_offset = &vcpu->kvm->arch.timer_data.voffset;
ptimer->vcpu = vcpu;
ptimer->offset.vm_offset = &vcpu->kvm->arch.timer_data.poffset;
/* Synchronize cntvoff across all vtimers of a VM. */
timer_set_offset(vtimer, kvm_phys_timer_read());
@ -1297,6 +1311,8 @@ void kvm_timer_init_vhe(void)
val = read_sysreg(cnthctl_el2);
val |= (CNTHCTL_EL1PCEN << cnthctl_shift);
val |= (CNTHCTL_EL1PCTEN << cnthctl_shift);
if (cpus_have_final_cap(ARM64_HAS_ECV_CNTPOFF))
val |= CNTHCTL_ECV;
write_sysreg(val, cnthctl_el2);
}

2
arch/arm64/kvm/hypercalls.c
View File

@ -47,7 +47,7 @@ static void kvm_ptp_get_time(struct kvm_vcpu *vcpu, u64 *val)
cycles = systime_snapshot.cycles - vcpu->kvm->arch.timer_data.voffset;
break;
case KVM_PTP_PHYS_COUNTER:
cycles = systime_snapshot.cycles;
cycles = systime_snapshot.cycles - vcpu->kvm->arch.timer_data.poffset;
break;
default:
return;

1
include/clocksource/arm_arch_timer.h
View File

@ -21,6 +21,7 @@
#define CNTHCTL_EVNTEN (1 << 2)
#define CNTHCTL_EVNTDIR (1 << 3)
#define CNTHCTL_EVNTI (0xF << 4)
#define CNTHCTL_ECV (1 << 12)
enum arch_timer_reg {
ARCH_TIMER_REG_CTRL,

2
include/kvm/arm_arch_timer.h
View File

@ -34,6 +34,8 @@ struct arch_timer_offset {
struct arch_timer_vm_data {
/* Offset applied to the virtual timer/counter */
u64 voffset;
/* Offset applied to the physical timer/counter */
u64 poffset;
};
struct arch_timer_context {