KVM: arm64: Extend unified RESx handling to runtime sanitisation

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, and additionally covers all sanitised
registers in all conditions, not just the VNCR-based ones.

Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Link: https://patch.msgid.link/20260202184329.2724080-6-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 799f494a1349c5d8f9f729a0d3657d3d39c48c96..20ebc1610ac8495b5ef6dd588d58a783cd46a1eb 100644 (file)
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -635,6 +635,21 @@ struct kvm_sysreg_masks {
        struct resx mask[NR_SYS_REGS - __SANITISED_REG_START__];
 };
 
+static inline struct resx __kvm_get_sysreg_resx(struct kvm_arch *arch,
+                                               enum vcpu_sysreg sr)
+{
+       struct kvm_sysreg_masks *masks;
+
+       masks = arch->sysreg_masks;
+       if (likely(masks &&
+                  sr >= __SANITISED_REG_START__ && sr < NR_SYS_REGS))
+               return masks->mask[sr - __SANITISED_REG_START__];
+
+       return (struct resx){};
+}
+
+#define kvm_get_sysreg_resx(k, sr) __kvm_get_sysreg_resx(&(k)->arch, (sr))
+
 static inline void __kvm_set_sysreg_resx(struct kvm_arch *arch,
                                         enum vcpu_sysreg sr, struct resx resx)
 {

diff --git a/arch/arm64/kvm/emulate-nested.c b/arch/arm64/kvm/emulate-nested.c
index 774cfbf5b43baa1621a316e61cad2105e6c5722f..43334cd2db9e5f45a5a6e8631afb8b9de1c365ed 100644 (file)
--- 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 c5a45bc62153e8b83e17283b211da11609a0aaaa..75a23f1c56d13c0e7767c761f2fb9101f69eab0a 100644 (file)
--- 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;
 }