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KVM: arm64: Move SPE availability check to VCPU load

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At the moment, we check the availability of SPE on the given
CPU (i.e, SPE is implemented and is allowed at the host) during
every guest entry. This can be optimized a bit by moving the
check to vcpu_load time and recording the availability of the
feature on the current CPU via a new flag. This will also be useful
for adding the TRBE support.

Cc: Marc Zyngier <maz@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: Alexandru Elisei <Alexandru.Elisei@arm.com>
Cc: James Morse <james.morse@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210405164307.1720226-7-suzuki.poulose@arm.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
This commit is contained in:
Suzuki K Poulose 2021-04-05 17:42:53 +01:00 committed by Mathieu Poirier
parent cc427cbb15
commit d2602bb4f5
4 changed files with 39 additions and 13 deletions
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5
arch/arm64/include/asm/kvm_host.h
View File

@ -400,6 +400,7 @@ struct kvm_vcpu_arch {
#define KVM_ARM64_GUEST_HAS_PTRAUTH (1 << 7) /* PTRAUTH exposed to guest */
#define KVM_ARM64_PENDING_EXCEPTION (1 << 8) /* Exception pending */
#define KVM_ARM64_EXCEPT_MASK (7 << 9) /* Target EL/MODE */
#define KVM_ARM64_DEBUG_STATE_SAVE_SPE (1 << 12) /* Save SPE context if active */
/*
* When KVM_ARM64_PENDING_EXCEPTION is set, KVM_ARM64_EXCEPT_MASK can
@ -734,6 +735,10 @@ static inline bool kvm_pmu_counter_deferred(struct perf_event_attr *attr)
return (!has_vhe() && attr->exclude_host);
}
/* Flags for host debug state */
void kvm_arch_vcpu_load_debug_state_flags(struct kvm_vcpu *vcpu);
void kvm_arch_vcpu_put_debug_state_flags(struct kvm_vcpu *vcpu);
#ifdef CONFIG_KVM /* Avoid conflicts with core headers if CONFIG_KVM=n */
static inline int kvm_arch_vcpu_run_pid_change(struct kvm_vcpu *vcpu)
{

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

@ -416,10 +416,12 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
if (vcpu_has_ptrauth(vcpu))
vcpu_ptrauth_disable(vcpu);
kvm_arch_vcpu_load_debug_state_flags(vcpu);
}
void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
{
kvm_arch_vcpu_put_debug_state_flags(vcpu);
kvm_arch_vcpu_put_fp(vcpu);
if (has_vhe())
kvm_vcpu_put_sysregs_vhe(vcpu);

23
arch/arm64/kvm/debug.c
View File

@ -231,3 +231,26 @@ void kvm_arm_clear_debug(struct kvm_vcpu *vcpu)
}
}
}
void kvm_arch_vcpu_load_debug_state_flags(struct kvm_vcpu *vcpu)
{
u64 dfr0;
/* For VHE, there is nothing to do */
if (has_vhe())
return;
dfr0 = read_sysreg(id_aa64dfr0_el1);
/*
* If SPE is present on this CPU and is available at current EL,
* we may need to check if the host state needs to be saved.
*/
if (cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_PMSVER_SHIFT) &&
!(read_sysreg_s(SYS_PMBIDR_EL1) & BIT(SYS_PMBIDR_EL1_P_SHIFT)))
vcpu->arch.flags |= KVM_ARM64_DEBUG_STATE_SAVE_SPE;
}
void kvm_arch_vcpu_put_debug_state_flags(struct kvm_vcpu *vcpu)
{
vcpu->arch.flags &= ~KVM_ARM64_DEBUG_STATE_SAVE_SPE;
}

22
arch/arm64/kvm/hyp/nvhe/debug-sr.c
View File

@ -21,17 +21,11 @@ static void __debug_save_spe(u64 *pmscr_el1)
/* Clear pmscr in case of early return */
*pmscr_el1 = 0;
/* SPE present on this CPU? */
if (!cpuid_feature_extract_unsigned_field(read_sysreg(id_aa64dfr0_el1),
ID_AA64DFR0_PMSVER_SHIFT))
return;
/* Yes; is it owned by EL3? */
reg = read_sysreg_s(SYS_PMBIDR_EL1);
if (reg & BIT(SYS_PMBIDR_EL1_P_SHIFT))
return;
/* No; is the host actually using the thing? */
/*
* At this point, we know that this CPU implements
* SPE and is available to the host.
* Check if the host is actually using it ?
*/
reg = read_sysreg_s(SYS_PMBLIMITR_EL1);
if (!(reg & BIT(SYS_PMBLIMITR_EL1_E_SHIFT)))
return;
@ -61,7 +55,8 @@ static void __debug_restore_spe(u64 pmscr_el1)
void __debug_save_host_buffers_nvhe(struct kvm_vcpu *vcpu)
{
/* Disable and flush SPE data generation */
__debug_save_spe(&vcpu->arch.host_debug_state.pmscr_el1);
if (vcpu->arch.flags & KVM_ARM64_DEBUG_STATE_SAVE_SPE)
__debug_save_spe(&vcpu->arch.host_debug_state.pmscr_el1);
}
void __debug_switch_to_guest(struct kvm_vcpu *vcpu)
@ -71,7 +66,8 @@ void __debug_switch_to_guest(struct kvm_vcpu *vcpu)
void __debug_restore_host_buffers_nvhe(struct kvm_vcpu *vcpu)
{
__debug_restore_spe(vcpu->arch.host_debug_state.pmscr_el1);
if (vcpu->arch.flags & KVM_ARM64_DEBUG_STATE_SAVE_SPE)
__debug_restore_spe(vcpu->arch.host_debug_state.pmscr_el1);
}
void __debug_switch_to_host(struct kvm_vcpu *vcpu)