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Fri, 27 Nov 2020 08:42:17 -0800 (PST) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id q12sm14859078wrx.86.2020.11.27.08.42.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 27 Nov 2020 08:42:17 -0800 (PST) From: Daniel Vetter To: DRI Development , LKML Subject: [PATCH v7 15/17] vfio/type1: Mark follow_pfn as unsafe Date: Fri, 27 Nov 2020 17:41:29 +0100 Message-Id: <20201127164131.2244124-16-daniel.vetter@ffwll.ch> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201127164131.2244124-1-daniel.vetter@ffwll.ch> References: <20201127164131.2244124-1-daniel.vetter@ffwll.ch> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201127_114218_995897_25D63D69 X-CRM114-Status: GOOD ( 19.15 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-samsung-soc@vger.kernel.org, Jan Kara , Kees Cook , kvm@vger.kernel.org, Jason Gunthorpe , Daniel Vetter , Cornelia Huck , Alex Williamson , linux-mm@kvack.org, =?utf-8?b?SsOpcsO0bWUgR2xpc3Nl?= , John Hubbard , Daniel Vetter , Dan Williams , Andrew Morton , linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org The code seems to stuff these pfns into iommu pts (or something like that, I didn't follow), but there's no mmu_notifier to ensure that access is synchronized with pte updates. Hence mark these as unsafe. This means that with CONFIG_STRICT_FOLLOW_PFN, these will be rejected. Real fix is to wire up an mmu_notifier ... somehow. Probably means any invalidate is a fatal fault for this vfio device, but then this shouldn't ever happen if userspace is reasonable. Signed-off-by: Daniel Vetter Cc: Jason Gunthorpe Cc: Kees Cook Cc: Dan Williams Cc: Andrew Morton Cc: John Hubbard Cc: Jérôme Glisse Cc: Jan Kara Cc: Dan Williams Cc: linux-mm@kvack.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-samsung-soc@vger.kernel.org Cc: linux-media@vger.kernel.org Cc: Alex Williamson Cc: Cornelia Huck Cc: kvm@vger.kernel.org Signed-off-by: Daniel Vetter --- drivers/vfio/vfio_iommu_type1.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index 67e827638995..10170723bb58 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -421,7 +421,7 @@ static int follow_fault_pfn(struct vm_area_struct *vma, struct mm_struct *mm, { int ret; - ret = follow_pfn(vma, vaddr, pfn); + ret = unsafe_follow_pfn(vma, vaddr, pfn); if (ret) { bool unlocked = false; @@ -435,7 +435,7 @@ static int follow_fault_pfn(struct vm_area_struct *vma, struct mm_struct *mm, if (ret) return ret; - ret = follow_pfn(vma, vaddr, pfn); + ret = unsafe_follow_pfn(vma, vaddr, pfn); } return ret;