[PATCH v4 27/40] KVM: arm64: Prepare to handle deferred save/restore of ELR_EL1

[Christoffer Dall]

ELR_EL1 is not used by a VHE host kernel and can be deferred, but we
need to rework the accesses to this register to access the latest value
depending on whether or not guest system registers are loaded on the CPU
or only reside in memory.

Signed-off-by: Christoffer Dall <christoffer.dall at linaro.org>
---

Notes:
    Changes since v2:
     - New patch (deferred register handling has been reworked)

 arch/arm64/include/asm/kvm_emulate.h | 18 +++++++++++++++++-
 arch/arm64/kvm/inject_fault.c        |  4 ++--
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
index 47c2406755fa..9cb13b23c7a1 100644
--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -90,11 +90,27 @@ static inline unsigned long *vcpu_pc(const struct kvm_vcpu *vcpu)
 	return (unsigned long *)&vcpu_gp_regs(vcpu)->regs.pc;
 }
 
-static inline unsigned long *vcpu_elr_el1(const struct kvm_vcpu *vcpu)
+static inline unsigned long *__vcpu_elr_el1(const struct kvm_vcpu *vcpu)
 {
 	return (unsigned long *)&vcpu_gp_regs(vcpu)->elr_el1;
 }
 
+static inline unsigned long vcpu_read_elr_el1(const struct kvm_vcpu *vcpu)
+{
+	if (vcpu->arch.sysregs_loaded_on_cpu)
+		return read_sysreg_el1(elr);
+	else
+		return *__vcpu_elr_el1(vcpu);
+}
+
+static inline void vcpu_write_elr_el1(const struct kvm_vcpu *vcpu, unsigned long v)
+{
+	if (vcpu->arch.sysregs_loaded_on_cpu)
+		write_sysreg_el1(v, elr);
+	else
+		*__vcpu_elr_el1(vcpu) = v;
+}
+
 static inline unsigned long *vcpu_cpsr(const struct kvm_vcpu *vcpu)
 {
 	return (unsigned long *)&vcpu_gp_regs(vcpu)->regs.pstate;
diff --git a/arch/arm64/kvm/inject_fault.c b/arch/arm64/kvm/inject_fault.c
index 8dda1edae727..cc13b6f5ad11 100644
--- a/arch/arm64/kvm/inject_fault.c
+++ b/arch/arm64/kvm/inject_fault.c
@@ -67,7 +67,7 @@ static void inject_abt64(struct kvm_vcpu *vcpu, bool is_iabt, unsigned long addr
 	bool is_aarch32 = vcpu_mode_is_32bit(vcpu);
 	u32 esr = 0;
 
-	*vcpu_elr_el1(vcpu) = *vcpu_pc(vcpu);
+	vcpu_write_elr_el1(vcpu, *vcpu_pc(vcpu));
 	*vcpu_pc(vcpu) = get_except_vector(vcpu, except_type_sync);
 
 	*vcpu_cpsr(vcpu) = PSTATE_FAULT_BITS_64;
@@ -102,7 +102,7 @@ static void inject_undef64(struct kvm_vcpu *vcpu)
 	unsigned long cpsr = *vcpu_cpsr(vcpu);
 	u32 esr = (ESR_ELx_EC_UNKNOWN << ESR_ELx_EC_SHIFT);
 
-	*vcpu_elr_el1(vcpu) = *vcpu_pc(vcpu);
+	vcpu_write_elr_el1(vcpu, *vcpu_pc(vcpu));
 	*vcpu_pc(vcpu) = get_except_vector(vcpu, except_type_sync);
 
 	*vcpu_cpsr(vcpu) = PSTATE_FAULT_BITS_64;
-- 
2.14.2