[PATCH 5.15 161/244] KVM: arm64: Reject 32bit user PSTATE on asymmetric systems

Greg Kroah-Hartman
2022-08-23T10:17:41Z

From: Oliver Upton <oliver.upton@linux.dev>

[ Upstream commit b10d86fb8e46cc812171728bcd326df2f34e9ed5 ]

KVM does not support AArch32 EL0 on asymmetric systems. To that end,
prevent userspace from configuring a vCPU in such a state through
setting PSTATE.

It is already ABI that KVM rejects such a write on a system where
AArch32 EL0 is unsupported. Though the kernel's definition of a 32bit
system changed in commit 2122a833316f ("arm64: Allow mismatched
32-bit EL0 support"), KVM's did not.

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/20220816192554.1455559-3-oliver.upton@linux.dev
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/arm64/kvm/guest.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 5ce26bedf23c..94108e2e0917 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -242,7 +242,7 @@ static int set_core_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
u64 mode = (*(u64 *)valp) & PSR_AA32_MODE_MASK;
switch (mode) {
case PSR_AA32_MODE_USR:
- if (!system_supports_32bit_el0())
+ if (!kvm_supports_32bit_el0())
return -EINVAL;
break;
case PSR_AA32_MODE_FIQ:
--
2.35.1