[PATCH 1/3] KVM: arm64: Configure HCRX_EL2 dynamically

[Kristina Martsenko]

At the moment the HCRX_EL2 system register is always initialized to
HCRX_GUEST_FLAGS when running a guest. Instead, choose the configuration
at vcpu reset time and save it in the vcpu struct, similarly to how
HCR_EL2 is set up. This will be needed in a subsequent change to
configure the register based on CPU features detected at runtime.

Signed-off-by: Kristina Martsenko <kristina.martsenko@xxxxxxx>
---
 arch/arm64/include/asm/kvm_emulate.h    | 5 +++++
 arch/arm64/include/asm/kvm_host.h       | 1 +
 arch/arm64/kvm/arm.c                    | 1 +
 arch/arm64/kvm/hyp/include/hyp/switch.h | 2 +-
 arch/arm64/kvm/hyp/nvhe/hyp-main.c      | 1 +
 arch/arm64/kvm/hyp/nvhe/pkvm.c          | 1 +
 6 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
index 3d6725ff0bf6..64ea27e6deb1 100644
--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -134,6 +134,11 @@ static inline void vcpu_ptrauth_disable(struct kvm_vcpu *vcpu)
 	vcpu->arch.hcr_el2 &= ~(HCR_API | HCR_APK);
 }
 
+static inline void vcpu_reset_hcrx(struct kvm_vcpu *vcpu)
+{
+	vcpu->arch.hcrx_el2 = HCRX_GUEST_FLAGS;
+}
+
 static inline unsigned long vcpu_get_vsesr(struct kvm_vcpu *vcpu)
 {
 	return vcpu->arch.vsesr_el2;
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index af06ccb7ee34..2764748756a7 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -487,6 +487,7 @@ struct kvm_vcpu_arch {
 
 	/* Values of trap registers for the guest. */
 	u64 hcr_el2;
+	u64 hcrx_el2;
 	u64 mdcr_el2;
 	u64 cptr_el2;
 
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 4866b3f7b4ea..fa359fd6fca9 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1318,6 +1318,7 @@ static int kvm_arch_vcpu_ioctl_vcpu_init(struct kvm_vcpu *vcpu,
 	}
 
 	vcpu_reset_hcr(vcpu);
+	vcpu_reset_hcrx(vcpu);
 	vcpu->arch.cptr_el2 = kvm_get_reset_cptr_el2(vcpu);
 
 	/*
diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
index 9cfe6bd1dbe4..119b75344505 100644
--- a/arch/arm64/kvm/hyp/include/hyp/switch.h
+++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
@@ -198,7 +198,7 @@ static inline void __activate_traps_common(struct kvm_vcpu *vcpu)
 	write_sysreg(vcpu->arch.mdcr_el2, mdcr_el2);
 
 	if (cpus_have_final_cap(ARM64_HAS_HCX)) {
-		u64 hcrx = HCRX_GUEST_FLAGS;
+		u64 hcrx = vcpu->arch.hcrx_el2;
 		if (vcpu_has_nv(vcpu) && !is_hyp_ctxt(vcpu)) {
 			u64 clr = 0, set = 0;
 
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index 857d9bc04fd4..26692083b80b 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -35,6 +35,7 @@ static void flush_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu)
 	hyp_vcpu->vcpu.arch.hw_mmu	= host_vcpu->arch.hw_mmu;
 
 	hyp_vcpu->vcpu.arch.hcr_el2	= host_vcpu->arch.hcr_el2;
+	hyp_vcpu->vcpu.arch.hcrx_el2	= host_vcpu->arch.hcrx_el2;
 	hyp_vcpu->vcpu.arch.mdcr_el2	= host_vcpu->arch.mdcr_el2;
 	hyp_vcpu->vcpu.arch.cptr_el2	= host_vcpu->arch.cptr_el2;
 
diff --git a/arch/arm64/kvm/hyp/nvhe/pkvm.c b/arch/arm64/kvm/hyp/nvhe/pkvm.c
index 8033ef353a5d..8c8b37525dce 100644
--- a/arch/arm64/kvm/hyp/nvhe/pkvm.c
+++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c
@@ -188,6 +188,7 @@ static void pvm_init_trap_regs(struct kvm_vcpu *vcpu)
 
 	/* Clear res0 and set res1 bits to trap potential new features. */
 	vcpu->arch.hcr_el2 &= ~(HCR_RES0);
+	vcpu->arch.hcrx_el2 &= ~(HCRX_EL2_RES0);
 	vcpu->arch.mdcr_el2 &= ~(MDCR_EL2_RES0);
 	if (!has_hvhe()) {
 		vcpu->arch.cptr_el2 |= CPTR_NVHE_EL2_RES1;
-- 
2.25.1