KVM: arm64: selftests: Alias EL1 registers to EL2 counterparts

FEAT_VHE has the somewhat nice property of implicitly redirecting EL1
register aliases to their corresponding EL2 representations when E2H=1.
Unfortunately, there's no such abstraction for userspace and EL2
registers are always accessed by their canonical encoding.

Introduce a helper that applies EL2 redirections to sysregs and use
aggressive inlining to catch misuse at compile time. Go a little past
the architectural definition for ease of use for test authors (e.g. the
stack pointer).

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>

4 files changed, 69 insertions, 11 deletions

diff --git a/tools/testing/selftests/kvm/arm64/vpmu_counter_access.c b/tools/testing/selftests/kvm/arm64/vpmu_counter_access.c
index 4a7e8e85a1b8..36a3a8b4e0b5 100644
--- a/tools/testing/selftests/kvm/arm64/vpmu_counter_access.c
+++ b/tools/testing/selftests/kvm/arm64/vpmu_counter_access.c
@@ -517,7 +517,7 @@ static void run_access_test(uint64_t pmcr_n)
 	vcpu = vpmu_vm.vcpu;
 
 	/* Save the initial sp to restore them later to run the guest again */
-	sp = vcpu_get_reg(vcpu, ARM64_CORE_REG(sp_el1));
+	sp = vcpu_get_reg(vcpu, ctxt_reg_alias(vcpu, SYS_SP_EL1));
 
 	run_vcpu(vcpu, pmcr_n);
 
@@ -529,7 +529,7 @@ static void run_access_test(uint64_t pmcr_n)
 	init.features[0] |= (1 << KVM_ARM_VCPU_PMU_V3);
 	aarch64_vcpu_setup(vcpu, &init);
 	vcpu_init_descriptor_tables(vcpu);
-	vcpu_set_reg(vcpu, ARM64_CORE_REG(sp_el1), sp);
+	vcpu_set_reg(vcpu, ctxt_reg_alias(vcpu, SYS_SP_EL1), sp);
 	vcpu_set_reg(vcpu, ARM64_CORE_REG(regs.pc), (uint64_t)guest_code);
 
 	run_vcpu(vcpu, pmcr_n);
diff --git a/tools/testing/selftests/kvm/include/arm64/processor.h b/tools/testing/selftests/kvm/include/arm64/processor.h
index 8c066ba1deb5..5a4b29c1b965 100644
--- a/tools/testing/selftests/kvm/include/arm64/processor.h
+++ b/tools/testing/selftests/kvm/include/arm64/processor.h
@@ -303,4 +303,58 @@ void wfi(void);
 void test_wants_mte(void);
 void test_disable_default_vgic(void);
 
+static bool vcpu_has_el2(struct kvm_vcpu *vcpu)
+{
+	return vcpu->init.features[0] & BIT(KVM_ARM_VCPU_HAS_EL2);
+}
+
+#define MAPPED_EL2_SYSREG(el2, el1)		\
+	case SYS_##el1:				\
+		if (vcpu_has_el2(vcpu))		\
+			alias = SYS_##el2;	\
+		break
+
+
+static __always_inline u64 ctxt_reg_alias(struct kvm_vcpu *vcpu, u32 encoding)
+{
+	u32 alias = encoding;
+
+	BUILD_BUG_ON(!__builtin_constant_p(encoding));
+
+	switch (encoding) {
+	MAPPED_EL2_SYSREG(SCTLR_EL2,		SCTLR_EL1);
+	MAPPED_EL2_SYSREG(CPTR_EL2,		CPACR_EL1);
+	MAPPED_EL2_SYSREG(TTBR0_EL2,		TTBR0_EL1);
+	MAPPED_EL2_SYSREG(TTBR1_EL2,		TTBR1_EL1);
+	MAPPED_EL2_SYSREG(TCR_EL2,		TCR_EL1);
+	MAPPED_EL2_SYSREG(VBAR_EL2,		VBAR_EL1);
+	MAPPED_EL2_SYSREG(AFSR0_EL2,		AFSR0_EL1);
+	MAPPED_EL2_SYSREG(AFSR1_EL2,		AFSR1_EL1);
+	MAPPED_EL2_SYSREG(ESR_EL2,		ESR_EL1);
+	MAPPED_EL2_SYSREG(FAR_EL2,		FAR_EL1);
+	MAPPED_EL2_SYSREG(MAIR_EL2,		MAIR_EL1);
+	MAPPED_EL2_SYSREG(TCR2_EL2,		TCR2_EL1);
+	MAPPED_EL2_SYSREG(PIR_EL2,		PIR_EL1);
+	MAPPED_EL2_SYSREG(PIRE0_EL2,		PIRE0_EL1);
+	MAPPED_EL2_SYSREG(POR_EL2,		POR_EL1);
+	MAPPED_EL2_SYSREG(AMAIR_EL2,		AMAIR_EL1);
+	MAPPED_EL2_SYSREG(ELR_EL2,		ELR_EL1);
+	MAPPED_EL2_SYSREG(SPSR_EL2,		SPSR_EL1);
+	MAPPED_EL2_SYSREG(ZCR_EL2,		ZCR_EL1);
+	MAPPED_EL2_SYSREG(CONTEXTIDR_EL2,	CONTEXTIDR_EL1);
+	MAPPED_EL2_SYSREG(SCTLR2_EL2,		SCTLR2_EL1);
+	MAPPED_EL2_SYSREG(CNTHCTL_EL2,		CNTKCTL_EL1);
+	case SYS_SP_EL1:
+		if (!vcpu_has_el2(vcpu))
+			return ARM64_CORE_REG(sp_el1);
+
+		alias = SYS_SP_EL2;
+		break;
+	default:
+		BUILD_BUG();
+	}
+
+	return KVM_ARM64_SYS_REG(alias);
+}
+
 #endif /* SELFTEST_KVM_PROCESSOR_H */
diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
index 3ab1fffbc3f2..11b6c5aa3f12 100644
--- a/tools/testing/selftests/kvm/include/kvm_util.h
+++ b/tools/testing/selftests/kvm/include/kvm_util.h
@@ -64,6 +64,9 @@ struct kvm_vcpu {
 #ifdef __x86_64__
 	struct kvm_cpuid2 *cpuid;
 #endif
+#ifdef __aarch64__
+	struct kvm_vcpu_init init;
+#endif
 	struct kvm_binary_stats stats;
 	struct kvm_dirty_gfn *dirty_gfns;
 	uint32_t fetch_index;
diff --git a/tools/testing/selftests/kvm/lib/arm64/processor.c b/tools/testing/selftests/kvm/lib/arm64/processor.c
index de77d9a7e0cd..311660a9f655 100644
--- a/tools/testing/selftests/kvm/lib/arm64/processor.c
+++ b/tools/testing/selftests/kvm/lib/arm64/processor.c
@@ -283,15 +283,16 @@ void aarch64_vcpu_setup(struct kvm_vcpu *vcpu, struct kvm_vcpu_init *init)
 	}
 
 	vcpu_ioctl(vcpu, KVM_ARM_VCPU_INIT, init);
+	vcpu->init = *init;
 
 	/*
 	 * Enable FP/ASIMD to avoid trapping when accessing Q0-Q15
 	 * registers, which the variable argument list macros do.
 	 */
-	vcpu_set_reg(vcpu, KVM_ARM64_SYS_REG(SYS_CPACR_EL1), 3 << 20);
+	vcpu_set_reg(vcpu, ctxt_reg_alias(vcpu, SYS_CPACR_EL1), 3 << 20);
 
-	sctlr_el1 = vcpu_get_reg(vcpu, KVM_ARM64_SYS_REG(SYS_SCTLR_EL1));
-	tcr_el1 = vcpu_get_reg(vcpu, KVM_ARM64_SYS_REG(SYS_TCR_EL1));
+	sctlr_el1 = vcpu_get_reg(vcpu, ctxt_reg_alias(vcpu, SYS_SCTLR_EL1));
+	tcr_el1 = vcpu_get_reg(vcpu, ctxt_reg_alias(vcpu, SYS_TCR_EL1));
 
 	/* Configure base granule size */
 	switch (vm->mode) {
@@ -358,10 +359,10 @@ void aarch64_vcpu_setup(struct kvm_vcpu *vcpu, struct kvm_vcpu_init *init)
 	if (use_lpa2_pte_format(vm))
 		tcr_el1 |= TCR_DS;
 
-	vcpu_set_reg(vcpu, KVM_ARM64_SYS_REG(SYS_SCTLR_EL1), sctlr_el1);
-	vcpu_set_reg(vcpu, KVM_ARM64_SYS_REG(SYS_TCR_EL1), tcr_el1);
-	vcpu_set_reg(vcpu, KVM_ARM64_SYS_REG(SYS_MAIR_EL1), DEFAULT_MAIR_EL1);
-	vcpu_set_reg(vcpu, KVM_ARM64_SYS_REG(SYS_TTBR0_EL1), ttbr0_el1);
+	vcpu_set_reg(vcpu, ctxt_reg_alias(vcpu, SYS_SCTLR_EL1), sctlr_el1);
+	vcpu_set_reg(vcpu, ctxt_reg_alias(vcpu, SYS_TCR_EL1), tcr_el1);
+	vcpu_set_reg(vcpu, ctxt_reg_alias(vcpu, SYS_MAIR_EL1), DEFAULT_MAIR_EL1);
+	vcpu_set_reg(vcpu, ctxt_reg_alias(vcpu, SYS_TTBR0_EL1), ttbr0_el1);
 	vcpu_set_reg(vcpu, KVM_ARM64_SYS_REG(SYS_TPIDR_EL1), vcpu->id);
 }
 
@@ -396,7 +397,7 @@ static struct kvm_vcpu *__aarch64_vcpu_add(struct kvm_vm *vm, uint32_t vcpu_id,
 
 	aarch64_vcpu_setup(vcpu, init);
 
-	vcpu_set_reg(vcpu, ARM64_CORE_REG(sp_el1), stack_vaddr + stack_size);
+	vcpu_set_reg(vcpu, ctxt_reg_alias(vcpu, SYS_SP_EL1), stack_vaddr + stack_size);
 	return vcpu;
 }
 
@@ -466,7 +467,7 @@ void vcpu_init_descriptor_tables(struct kvm_vcpu *vcpu)
 {
 	extern char vectors;
 
-	vcpu_set_reg(vcpu, KVM_ARM64_SYS_REG(SYS_VBAR_EL1), (uint64_t)&vectors);
+	vcpu_set_reg(vcpu, ctxt_reg_alias(vcpu, SYS_VBAR_EL1), (uint64_t)&vectors);
 }
 
 void route_exception(struct ex_regs *regs, int vector)