From 33d85a93c6c3c0c1fc2d168ee5a9ae604c439fa7 Mon Sep 17 00:00:00 2001 From: Oliver Upton Date: Fri, 21 Jun 2024 22:40:44 +0000 Subject: [PATCH] KVM: arm64: nv: Unfudge ID_AA64PFR0_EL1 masking Marc reports that L1 VMs aren't booting with the NV series applied to today's kvmarm/next. After bisecting the issue, it appears that 44241f34fac9 ("KVM: arm64: nv: Use accessors for modifying ID registers") is to blame. Poking around at the issue a bit further, it'd appear that the value for ID_AA64PFR0_EL1 is complete garbage, as 'val' still contains the value we set ID_AA64ISAR1_EL1 to. Fix the read-modify-write pattern to actually use ID_AA64PFR0_EL1 as the starting point. Excuse me as I return to my shame cube. Reported-by: Marc Zyngier Fixes: 44241f34fac9 ("KVM: arm64: nv: Use accessors for modifying ID registers") Acked-by: Marc Zyngier Tested-by: Marc Zyngier Link: https://lore.kernel.org/r/20240621224044.2465901-1-oliver.upton@linux.dev Signed-off-by: Oliver Upton --- arch/arm64/kvm/nested.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c index 44085c13e673..794ed18c0537 100644 --- a/arch/arm64/kvm/nested.c +++ b/arch/arm64/kvm/nested.c @@ -40,7 +40,7 @@ static void limit_nv_id_regs(struct kvm *kvm) kvm_set_vm_id_reg(kvm, SYS_ID_AA64ISAR1_EL1, val); /* No AMU, MPAM, S-EL2, RAS or SVE */ - kvm_read_vm_id_reg(kvm, SYS_ID_AA64PFR0_EL1); + val = kvm_read_vm_id_reg(kvm, SYS_ID_AA64PFR0_EL1); val &= ~(GENMASK_ULL(55, 52) | NV_FTR(PFR0, AMU) | NV_FTR(PFR0, MPAM) | -- 2.50.1