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[54.240.197.234]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4b2a5372d8bsm87303325e9.0.2026.11.03.11.38.50 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 03 Nov 2026 11:38:50 -0800 (PST) From: Fred Griffoul To: "Aneesh Kumar K.V (Arm)" , linux-coco@lists.linux.dev Cc: Ackerley Tng , Alex Williamson , David Woodhouse , David Hildenbrand , Jason Gunthorpe , "Joerg Roedel (AMD)" , Kevin Tian , Paolo Bonzini , Robin Murphy , Sean Christopherson , Will Deacon , Alexey Kardashevskiy , Xu Yilun , Catalin Marinas , Suzuki K Poulose , Steven Price , iommu@lists.linux.dev, kvm@vger.kernel.org, patches@lists.linux.dev Subject: Re: [RFC PATCH v3 07/13] KVM: guest_memfd: Support private/shared conversion of device memory Date: Tue, 3 Nov 2026 19:38:50 +0000 Message-ID: <20261103193850.15363-1-griffoul@gmail.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20261101071928.2462549-8-aneesh.kumar@kernel.org> References: <20261101071928.2462549-8-aneesh.kumar@kernel.org> X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit "Aneesh Kumar K.V (Arm)" writes: > + if (!slot) > + return -EINVAL; [...] > + ret = kvm_arch_gmem_device_map(gi->device.kvm, slot, gpa, > + (u64)(high - first) << PAGE_SHIFT, > + PFN_PHYS(pfn)); > + if (ret) > + return ret; Unless I'm missing something, these returns leave the pieces already mapped in place, while the attributes stay shared. A later conversion to shared would then find nothing to do, and a retry of this conversion would run into the pieces that are mapped. Would it make sense for the error path to unmap what was mapped, e.g. with kvm_gmem_invalidate_start() and KVM_FILTER_PRIVATE on the range? Fred