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KVM: arm64: timers: Fast-track CNTPCT_EL0 trap handling

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Now that it is likely that CNTPCT_EL0 accesses will trap,
fast-track the emulation of the counter read which doesn't
need more that a simple offsetting.

One day, we'll have CNTPOFF everywhere. One day.

Suggested-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230330174800.2677007-14-maz@kernel.org
This commit is contained in:
Marc Zyngier 2023-03-30 18:47:53 +01:00
parent 1a6511eb84
commit e9adde432b
1 changed files with 36 additions and 0 deletions
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36
arch/arm64/kvm/hyp/include/hyp/switch.h
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@ -26,6 +26,7 @@
#include <asm/kvm_emulate.h>
#include <asm/kvm_hyp.h>
#include <asm/kvm_mmu.h>
#include <asm/kvm_nested.h>
#include <asm/fpsimd.h>
#include <asm/debug-monitors.h>
#include <asm/processor.h>
@ -326,6 +327,38 @@ static bool kvm_hyp_handle_ptrauth(struct kvm_vcpu *vcpu, u64 *exit_code)
return true;
}
static bool kvm_hyp_handle_cntpct(struct kvm_vcpu *vcpu)
{
struct arch_timer_context *ctxt;
u32 sysreg;
u64 val;
/*
* We only get here for 64bit guests, 32bit guests will hit
* the long and winding road all the way to the standard
* handling. Yes, it sucks to be irrelevant.
*/
sysreg = esr_sys64_to_sysreg(kvm_vcpu_get_esr(vcpu));
switch (sysreg) {
case SYS_CNTPCT_EL0:
case SYS_CNTPCTSS_EL0:
ctxt = vcpu_ptimer(vcpu);
break;
default:
return false;
}
val = arch_timer_read_cntpct_el0();
if (ctxt->offset.vm_offset)
val -= *kern_hyp_va(ctxt->offset.vm_offset);
vcpu_set_reg(vcpu, kvm_vcpu_sys_get_rt(vcpu), val);
__kvm_skip_instr(vcpu);
return true;
}
static bool kvm_hyp_handle_sysreg(struct kvm_vcpu *vcpu, u64 *exit_code)
{
if (cpus_have_final_cap(ARM64_WORKAROUND_CAVIUM_TX2_219_TVM) &&
@ -339,6 +372,9 @@ static bool kvm_hyp_handle_sysreg(struct kvm_vcpu *vcpu, u64 *exit_code)
if (esr_is_ptrauth_trap(kvm_vcpu_get_esr(vcpu)))
return kvm_hyp_handle_ptrauth(vcpu, exit_code);
if (kvm_hyp_handle_cntpct(vcpu))
return true;
return false;
}