arm64: KVM: Sanitize PSTATE.M when being set from userspace

Not all execution modes are valid for a guest, and some of them
depend on what the HW actually supports. Let's verify that what
userspace provides is compatible with both the VM settings and
the HW capabilities.

Cc: <stable@vger.kernel.org>
Fixes: 0d854a60b1d7 ("arm64: KVM: enable initialization of a 32bit vcpu")
Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 3088463bafc1fa2681fa6c371883e22cc8351330..a6c9fbaeaefcdd71d0ea70c8eeb89c55692f8b66 100644 (file)
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -152,17 +152,25 @@ static int set_core_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
        }
 
        if (off == KVM_REG_ARM_CORE_REG(regs.pstate)) {
-               u32 mode = (*(u32 *)valp) & PSR_AA32_MODE_MASK;
+               u64 mode = (*(u64 *)valp) & PSR_AA32_MODE_MASK;
                switch (mode) {
                case PSR_AA32_MODE_USR:
+                       if (!system_supports_32bit_el0())
+                               return -EINVAL;
+                       break;
                case PSR_AA32_MODE_FIQ:
                case PSR_AA32_MODE_IRQ:
                case PSR_AA32_MODE_SVC:
                case PSR_AA32_MODE_ABT:
                case PSR_AA32_MODE_UND:
+                       if (!vcpu_el1_is_32bit(vcpu))
+                               return -EINVAL;
+                       break;
                case PSR_MODE_EL0t:
                case PSR_MODE_EL1t:
                case PSR_MODE_EL1h:
+                       if (vcpu_el1_is_32bit(vcpu))
+                               return -EINVAL;
                        break;
                default:
                        err = -EINVAL;