KVM: arm64: Treat PMCR_EL1.LC as RES1 on asymmetric systems

KVM does not support AArch32 on asymmetric systems. To that end, enforce
AArch64-only behavior on PMCR_EL1.LC when on an asymmetric system.

Fixes: 2122a833316f ("arm64: Allow mismatched 32-bit EL0 support")
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220816192554.1455559-2-oliver.upton@linux.dev

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index f38ef29..e9c9388 100644 (file)
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -929,6 +929,10 @@ bool kvm_arm_vcpu_is_finalized(struct kvm_vcpu *vcpu);
        (system_supports_mte() &&                               \
         test_bit(KVM_ARCH_FLAG_MTE_ENABLED, &(kvm)->arch.flags))
 
+#define kvm_supports_32bit_el0()                               \
+       (system_supports_32bit_el0() &&                         \
+        !static_branch_unlikely(&arm64_mismatched_32bit_el0))
+
 int kvm_trng_call(struct kvm_vcpu *vcpu);
 #ifdef CONFIG_KVM
 extern phys_addr_t hyp_mem_base;

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 8fe73ee..e508b61 100644 (file)
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -757,8 +757,7 @@ static bool vcpu_mode_is_bad_32bit(struct kvm_vcpu *vcpu)
        if (likely(!vcpu_mode_is_32bit(vcpu)))
                return false;
 
-       return !system_supports_32bit_el0() ||
-               static_branch_unlikely(&arm64_mismatched_32bit_el0);
+       return !kvm_supports_32bit_el0();
 }
 
 /**

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 333efdd..3c4f5c9 100644 (file)
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -652,7 +652,7 @@ static void reset_pmcr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
         */
        val = ((pmcr & ~ARMV8_PMU_PMCR_MASK)
               | (ARMV8_PMU_PMCR_MASK & 0xdecafbad)) & (~ARMV8_PMU_PMCR_E);
-       if (!system_supports_32bit_el0())
+       if (!kvm_supports_32bit_el0())
                val |= ARMV8_PMU_PMCR_LC;
        __vcpu_sys_reg(vcpu, r->reg) = val;
 }
@@ -701,7 +701,7 @@ static bool access_pmcr(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
                val = __vcpu_sys_reg(vcpu, PMCR_EL0);
                val &= ~ARMV8_PMU_PMCR_MASK;
                val |= p->regval & ARMV8_PMU_PMCR_MASK;
-               if (!system_supports_32bit_el0())
+               if (!kvm_supports_32bit_el0())
                        val |= ARMV8_PMU_PMCR_LC;
                __vcpu_sys_reg(vcpu, PMCR_EL0) = val;
                kvm_pmu_handle_pmcr(vcpu, val);