KVM: arm/arm64: Add kvm_vcpu_load_sysregs and kvm_vcpu_put_sysregs

As we are about to move a bunch of save/restore logic for VHE kernels to
the load and put functions, we need some infrastructure to do this.

Reviewed-by: Andrew Jones <drjones@redhat.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index 6137195ab815a6dc6a4d2c53fbf2e17aa9f0bacc..c6a749568dd6c413603ef3b7554561f356b33cc9 100644 (file)
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -312,4 +312,7 @@ static inline bool kvm_arm_harden_branch_predictor(void)
        return false;
 }
 
+static inline void kvm_vcpu_load_sysregs(struct kvm_vcpu *vcpu) {}
+static inline void kvm_vcpu_put_sysregs(struct kvm_vcpu *vcpu) {}
+
 #endif /* __ARM_KVM_HOST_H__ */

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index b027a7f025d43499d969873984f6cb9a142b432a..c30fc96992dfe7847f3c6dfb1e72fbbdd4fd9eab 100644 (file)
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -435,4 +435,7 @@ static inline bool kvm_arm_harden_branch_predictor(void)
        return cpus_have_const_cap(ARM64_HARDEN_BRANCH_PREDICTOR);
 }
 
+void kvm_vcpu_load_sysregs(struct kvm_vcpu *vcpu);
+void kvm_vcpu_put_sysregs(struct kvm_vcpu *vcpu);
+
 #endif /* __ARM64_KVM_HOST_H__ */

diff --git a/arch/arm64/kvm/hyp/sysreg-sr.c b/arch/arm64/kvm/hyp/sysreg-sr.c
index 43b7dd65e3e685504f2ea33ee81e1cd6754b62f4..434f0fc9cfb359f851941cda1ac535aabc5cdca4 100644 (file)
--- a/arch/arm64/kvm/hyp/sysreg-sr.c
+++ b/arch/arm64/kvm/hyp/sysreg-sr.c
@@ -190,6 +190,36 @@ void __hyp_text __sysreg32_restore_state(struct kvm_vcpu *vcpu)
                write_sysreg(sysreg[DBGVCR32_EL2], dbgvcr32_el2);
 }
 
+/**
+ * kvm_vcpu_load_sysregs - Load guest system registers to the physical CPU
+ *
+ * @vcpu: The VCPU pointer
+ *
+ * Load system registers that do not affect the host's execution, for
+ * example EL1 system registers on a VHE system where the host kernel
+ * runs at EL2.  This function is called from KVM's vcpu_load() function
+ * and loading system register state early avoids having to load them on
+ * every entry to the VM.
+ */
+void kvm_vcpu_load_sysregs(struct kvm_vcpu *vcpu)
+{
+}
+
+/**
+ * kvm_vcpu_put_sysregs - Restore host system registers to the physical CPU
+ *
+ * @vcpu: The VCPU pointer
+ *
+ * Save guest system registers that do not affect the host's execution, for
+ * example EL1 system registers on a VHE system where the host kernel
+ * runs at EL2.  This function is called from KVM's vcpu_put() function
+ * and deferring saving system register state until we're no longer running the
+ * VCPU avoids having to save them on every exit from the VM.
+ */
+void kvm_vcpu_put_sysregs(struct kvm_vcpu *vcpu)
+{
+}
+
 void __hyp_text __kvm_set_tpidr_el2(u64 tpidr_el2)
 {
        asm("msr tpidr_el2, %0": : "r" (tpidr_el2));

diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
index 49d13510e9c2829f915327187f13b1ab615a7f20..2062d93579717769fb9e2998120cb2832e246d0c 100644 (file)
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c
@@ -362,10 +362,12 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
        kvm_arm_set_running_vcpu(vcpu);
        kvm_vgic_load(vcpu);
        kvm_timer_vcpu_load(vcpu);
+       kvm_vcpu_load_sysregs(vcpu);
 }
 
 void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
 {
+       kvm_vcpu_put_sysregs(vcpu);
        kvm_timer_vcpu_put(vcpu);
        kvm_vgic_put(vcpu);