Commit 7af7cfbe authored by Marc Zyngier's avatar Marc Zyngier Committed by Oliver Upton
Browse files

KVM: arm64: Prevent userspace from disabling AArch64 support at any virtualisable EL 



A sorry excuse for a selftest is trying to disable AArch64 support.
And yes, this goes as well as you can imagine.

Let's forbid this sort of things. Normal userspace shouldn't get
caught doing that.

Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Reviewed-by: default avatarGanapatrao Kulkarni <gankulkarni@os.amperecomputing.com>
Link: https://lore.kernel.org/r/20250429114117.3618800-2-maz@kernel.org


Signed-off-by: default avatarOliver Upton <oliver.upton@linux.dev>
parent 859c6027

arch/arm64/kvm/sys_regs.c

+6 −0
Original line number Diff line number Diff line
@@ -1945,6 +1945,12 @@ static int set_id_aa64pfr0_el1(struct kvm_vcpu *vcpu, 
	if ((hw_val & mpam_mask) == (user_val & mpam_mask))

		user_val &= ~ID_AA64PFR0_EL1_MPAM_MASK;



	/* Fail the guest's request to disable the AA64 ISA at EL{0,1,2} */

	if (!FIELD_GET(ID_AA64PFR0_EL1_EL0, user_val) ||

	    !FIELD_GET(ID_AA64PFR0_EL1_EL1, user_val) ||

	    (vcpu_has_nv(vcpu) && !FIELD_GET(ID_AA64PFR0_EL1_EL2, user_val)))

		return -EINVAL;



	return set_id_reg(vcpu, rd, user_val);

}