[PATCH v2 09/11] arm64: KVM: Make PSCI_VERSION a fast path

Will Deacon
2018-01-05T13:12:39Z

From: Marc Zyngier <marc.zyngier@arm.com>

For those CPUs that require PSCI to perform a BP invalidation,
going all the way to the PSCI code for not much is a waste of
precious cycles. Let's terminate that call as early as possible.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
---
arch/arm64/kvm/hyp/switch.c | 13 +++++++++++++
1 file changed, 13 insertions(+)

diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
index 8d4f3c9d6dc4..4d273f6d0e69 100644
--- a/arch/arm64/kvm/hyp/switch.c
+++ b/arch/arm64/kvm/hyp/switch.c
@@ -17,6 +17,7 @@

#include <linux/types.h>
#include <linux/jump_label.h>
+#include <uapi/linux/psci.h>

#include <asm/kvm_asm.h>
#include <asm/kvm_emulate.h>
@@ -341,6 +342,18 @@ int __hyp_text __kvm_vcpu_run(struct kvm_vcpu *vcpu)
if (exit_code == ARM_EXCEPTION_TRAP && !__populate_fault_info(vcpu))
goto again;

+ if (exit_code == ARM_EXCEPTION_TRAP &&
+ (kvm_vcpu_trap_get_class(vcpu) == ESR_ELx_EC_HVC64 ||
+ kvm_vcpu_trap_get_class(vcpu) == ESR_ELx_EC_HVC32) &&
+ vcpu_get_reg(vcpu, 0) == PSCI_0_2_FN_PSCI_VERSION) {
+ u64 val = PSCI_RET_NOT_SUPPORTED;
+ if (test_bit(KVM_ARM_VCPU_PSCI_0_2, vcpu->arch.features))
+ val = 2;
+
+ vcpu_set_reg(vcpu, 0, val);
+ goto again;
+ }
+
if (static_branch_unlikely(&vgic_v2_cpuif_trap) &&
exit_code == ARM_EXCEPTION_TRAP) {
bool valid;
--
2.1.4