Re: [PATCH 10/12] KVM: arm64: nv: Add SW walker for AT S1 emulation

[Marc Zyngier <maz@kernel.org>]

On Thu, 25 Jul 2024 15:16:12 +0100,
Alexandru Elisei <alexandru.elisei@arm.com> wrote:
> 
> Hi Marc,
> 
> On Mon, Jul 08, 2024 at 05:57:58PM +0100, Marc Zyngier wrote:
> > +	if (perm_fail) {
> > +		struct s1_walk_result tmp;
> 
> I was wondering if you would consider initializing 'tmp' to the empty struct
> here. That makes it consistent with the initialization of 'wr' in the !perm_fail
> case and I think it will make the code more robust wrt to changes to
> compute_par_s1() and what fields it accesses.

I think there is a slightly better way, with something like this:

diff --git a/arch/arm64/kvm/at.c b/arch/arm64/kvm/at.c
index b02d8dbffd209..36fa2801ab4ef 100644
--- a/arch/arm64/kvm/at.c
+++ b/arch/arm64/kvm/at.c
@@ -803,12 +803,12 @@ static u64 handle_at_slow(struct kvm_vcpu *vcpu, u32 op, u64 vaddr)
 	}
 
 	if (perm_fail) {
-		struct s1_walk_result tmp;
-
-		tmp.failed = true;
-		tmp.fst = ESR_ELx_FSC_PERM | wr.level;
-		tmp.s2 = false;
-		tmp.ptw = false;
+		struct s1_walk_result tmp = (struct s1_walk_result){
+			.failed	= true,
+			.fst	= ESR_ELx_FSC_PERM | wr.level,
+			.s2	= false,
+			.ptw	= false,
+		};
 
 		wr = tmp;
 	}

Thoughts?

	M.

-- 
Without deviation from the norm, progress is not possible.