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 <m...@kernel.org>
Cc: Will Deacon <w...@kernel.org>
Cc: Alexandru Elisei <alexandru.eli...@arm.com>
Cc: James Morse <james.mo...@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poul...@arm.com>
---
arch/arm64/include/asm/kvm_host.h | 5 +++++
arch/arm64/kvm/arm.c | 2 ++
arch/arm64/kvm/debug.c | 23 +++++++++++++++++++++++
arch/arm64/kvm/hyp/nvhe/debug-sr.c | 22 +++++++++-------------
4 files changed, 39 insertions(+), 13 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_host.h
b/arch/arm64/include/asm/kvm_host.h
index 3d10e6527f7d..acc2b45dd433 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -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)
{
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 7f06ba76698d..954752208509 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -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);
diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c
index dbc890511631..b6d2c33ad1df 100644
--- a/arch/arm64/kvm/debug.c
+++ b/arch/arm64/kvm/debug.c
@@ -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;
+}
diff --git a/arch/arm64/kvm/hyp/nvhe/debug-sr.c
b/arch/arm64/kvm/hyp/nvhe/debug-sr.c
index f401724f12ef..e6ee9b7faec6 100644
--- a/arch/arm64/kvm/hyp/nvhe/debug-sr.c
+++ b/arch/arm64/kvm/hyp/nvhe/debug-sr.c
@@ -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)
--
2.24.1
