Subject: [PATCH v4 03/46] KVM: PPC: Book3S HV: Disallow LPCR[AIL] to be set to 1 or 2

From: Nicholas Piggin <[email-masked]>
Date: Tue, 23 Mar 2021 11:02:22 +1000

These are already disallowed by H_SET_MODE from the guest, also disallow
these by updating LPCR directly.

AIL modes can affect the host interrupt behaviour while the guest LPCR
value is set, so filter it here too.

Suggested-by: Fabiano Rosas <[email-masked]>
Signed-off-by: Nicholas Piggin <[email-masked]>
---
 arch/powerpc/kvm/book3s_hv.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index c4539c38c639..c5de7e3f22b6 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -803,7 +803,10 @@ static int kvmppc_h_set_mode(struct kvm_vcpu *vcpu, unsigned long mflags,
 		vcpu->arch.dawrx1 = value2;
 		return H_SUCCESS;
 	case H_SET_MODE_RESOURCE_ADDR_TRANS_MODE:
-		/* KVM does not support mflags=2 (AIL=2) */
+		/*
+		 * KVM does not support mflags=2 (AIL=2) and AIL=1 is reserved.
+		 * Keep this in synch with kvmppc_filter_guest_lpcr_hv.
+		 */
 		if (mflags != 0 && mflags != 3)
 			return H_UNSUPPORTED_FLAG_START;
 		return H_TOO_HARD;
@@ -1645,6 +1648,8 @@ unsigned long kvmppc_filter_lpcr_hv(struct kvmppc_vcore *vc, unsigned long lpcr)
 	/* On POWER8 and above, userspace can modify AIL */
 	if (!cpu_has_feature(CPU_FTR_ARCH_207S))
 		lpcr &= ~LPCR_AIL;
+	if ((lpcr & LPCR_AIL) != LPCR_AIL_3)
+		lpcr &= ~LPCR_AIL; /* LPCR[AIL]=1/2 is disallowed */
 
 	/*
 	 * On POWER9, allow userspace to enable large decrementer for the
-- 
2.23.0