[PATCH 05/20] KVM: arm64: Extend unified RESx handling to runtime sanitisation

[Marc Zyngier]

Add a new helper to retrieve the RESx values for a given system
register, and use it for the runtime sanitisation.

This results in slightly better code generation for a fairly hot
path in the hypervisor.

Signed-off-by: Marc Zyngier <maz at kernel.org>
---
 arch/arm64/include/asm/kvm_host.h | 13 +++++++++++++
 arch/arm64/kvm/emulate-nested.c   | 10 +---------
 arch/arm64/kvm/nested.c           | 13 ++++---------
 3 files changed, 18 insertions(+), 18 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index a7e4cd8ebf56f..9dca94e4361f0 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -635,6 +635,19 @@ struct kvm_sysreg_masks {
 	struct resx mask[NR_SYS_REGS - __SANITISED_REG_START__];
 };
 
+#define kvm_get_sysreg_resx(k, sr)					\
+	({                                                              \
+		struct kvm_sysreg_masks *__masks;			\
+		struct resx __resx = {};				\
+									\
+		__masks = (k)->arch.sysreg_masks;			\
+		if (likely(__masks &&					\
+			   sr >= __SANITISED_REG_START__ &&		\
+			   sr < NR_SYS_REGS))				\
+			__resx = __masks->mask[sr - __SANITISED_REG_START__]; \
+		__resx;							\
+	})
+
 #define kvm_set_sysreg_resx(k, sr, resx)		\
 	do {						\
 		(k)->arch.sysreg_masks->mask[sr - __SANITISED_REG_START__] = resx; \
diff --git a/arch/arm64/kvm/emulate-nested.c b/arch/arm64/kvm/emulate-nested.c
index 774cfbf5b43ba..43334cd2db9e5 100644
--- a/arch/arm64/kvm/emulate-nested.c
+++ b/arch/arm64/kvm/emulate-nested.c
@@ -2427,15 +2427,7 @@ static enum trap_behaviour compute_trap_behaviour(struct kvm_vcpu *vcpu,
 
 static u64 kvm_get_sysreg_res0(struct kvm *kvm, enum vcpu_sysreg sr)
 {
-	struct kvm_sysreg_masks *masks;
-
-	/* Only handle the VNCR-backed regs for now */
-	if (sr < __VNCR_START__)
-		return 0;
-
-	masks = kvm->arch.sysreg_masks;
-
-	return masks->mask[sr - __SANITISED_REG_START__].res0;
+	return kvm_get_sysreg_resx(kvm, sr).res0;
 }
 
 static bool check_fgt_bit(struct kvm_vcpu *vcpu, enum vcpu_sysreg sr,
diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c
index c5a45bc62153e..75a23f1c56d13 100644
--- a/arch/arm64/kvm/nested.c
+++ b/arch/arm64/kvm/nested.c
@@ -1669,16 +1669,11 @@ u64 limit_nv_id_reg(struct kvm *kvm, u32 reg, u64 val)
 u64 kvm_vcpu_apply_reg_masks(const struct kvm_vcpu *vcpu,
 			     enum vcpu_sysreg sr, u64 v)
 {
-	struct kvm_sysreg_masks *masks;
-
-	masks = vcpu->kvm->arch.sysreg_masks;
-
-	if (masks) {
-		sr -= __SANITISED_REG_START__;
+	struct resx resx;
 
-		v &= ~masks->mask[sr].res0;
-		v |= masks->mask[sr].res1;
-	}
+	resx = kvm_get_sysreg_resx(vcpu->kvm, sr);
+	v &= ~resx.res0;
+	v |= resx.res1;
 
 	return v;
 }
-- 
2.47.3