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[159.2.239.150]) by smtp.gmail.com with ESMTPSA id af79cd13be357-93720493f40sm418053785a.1.2026.08.20.10.47.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 Aug 2026 10:47:40 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1wx6rb-00000004ADY-1Cil; Thu, 20 Aug 2026 14:47:39 -0300 Date: Thu, 20 Aug 2026 14:47:39 -0300 From: Jason Gunthorpe To: Catalin Marinas Cc: Steven Price , Christian =?utf-8?B?S8O2bmln?= , Marc Zyngier , Sumit Semwal , Thomas Gleixner , "T.J. Mercier" , Benjamin Gaignard , Brian Starkey , John Stultz , dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, Jiri Pirko , Marek Szyprowski , Suzuki K Poulose Subject: Re: [PATCH v2 1/4] irqchip/gic-v3-its: Zero shared pages after conversion Message-ID: <20260820174739.GA981928@ziepe.ca> References: <20260820150034.88729-1-steven.price@arm.com> <20260820150034.88729-2-steven.price@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260820_104742_508913_B18861D9 X-CRM114-Status: GOOD ( 15.55 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Aug 20, 2026 at 06:44:43PM +0100, Catalin Marinas wrote: > On Thu, Aug 20, 2026 at 04:00:30PM +0100, Steven Price wrote: > > diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c > > index 6f5811aae59c..a055837832bc 100644 > > --- a/drivers/irqchip/irq-gic-v3-its.c > > +++ b/drivers/irqchip/irq-gic-v3-its.c > > @@ -213,16 +213,18 @@ static gfp_t gfp_flags_quirk; > > static struct page *its_alloc_pages_node(int node, gfp_t gfp, > > unsigned int order) > > { > > + bool want_zero = gfp & __GFP_ZERO; > > struct page *page; > > int ret = 0; > > > > - page = alloc_pages_node(node, gfp | gfp_flags_quirk, order); > > + page = alloc_pages_node(node, (gfp & ~__GFP_ZERO) | gfp_flags_quirk, > > + order); > > I don't think pKVM does any scrubbing on set_memory_decrypted(), so it > potentially exposes confidential guest data before it reaches > clear_pages() below. IMHO that has got to be handled in the arch code implementing set memory decrypted. Further pointing that maybe we should have an alloc decrypted so we can at least try to minimize the number of times we write to this memory. :( Jason