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Tue, 10 Nov 2026 05:38:38 -0800 (PST) Received: from localhost ([2c0f:3d00:6be:8900:ce5e:9212:ea4b:f30]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-49835c37bdfsm5292609f8f.22.2026.11.10.05.38.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Nov 2026 05:38:38 -0800 (PST) Date: Tue, 10 Nov 2026 16:38:34 +0300 From: Dan Carpenter To: Marc Zyngier Cc: Eric Auger , Oliver Upton , Fuad Tabba , Joey Gouly , Steffen Eiden , Suzuki K Poulose , Zenghui Yu , Catalin Marinas , Will Deacon , Mark Rutland , Carlos =?iso-8859-1?Q?L=F3pez?= , Sascha Bischoff , Jackie Liu , Christoffer Dall , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, Karthik Bhargavan , =?iso-8859-1?Q?Cl=E9ment?= Blaudeau Subject: Re: [PATCH] KVM: arm64: vgic-its: Reject ITS_REGS offsets above U32_MAX Message-ID: References: <86wlql0x5t.wl-maz@kernel.org> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <86wlql0x5t.wl-maz@kernel.org> On Tue, Nov 10, 2026 at 10:59:42AM +0000, Marc Zyngier wrote: > > + if (offset > U32_MAX) > > + return -ENXIO; > > + > > /* > > * Although the spec supports upper/lower 32-bit accesses to > > * 64-bit ITS registers, the userspace ABI requires 64-bit > > I think this is going in the wrong direction. Instead of capping the > offset at an arbitrary value, the infrastructure should be able to > deal with arbitrary offsets. > > Could you try the following (untested) hack? > > I also don't think this is worth a Cc stable (the worse case is that > the VMM accesses an emulated register and sets something nonsensical), > which it can always do. Fair enough. We are in arch/arm64/ so casting a u64 to a pointer and back works. Except for these two, the other callers pass values which fit in a u32 so they aren't affected. I'm going to remove some of your casts which aren't necessary and add the uintptr_t cast back. regards, dan carpenter