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Wed, 23 Sep 2026 08:21:25 -0700 (PDT) Received: from ziepe.ca ([130.41.10.202]) by smtp.gmail.com with ESMTPSA id af79cd13be357-93c277636e4sm181224485a.41.2026.09.23.08.21.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 23 Sep 2026 08:21:25 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1x9Omi-0000000DrJM-1RIj; Wed, 23 Sep 2026 12:21:24 -0300 Date: Wed, 23 Sep 2026 12:21:24 -0300 From: Jason Gunthorpe To: "Aneesh Kumar K.V" Cc: Catalin Marinas , linux-coco@lists.linux.dev, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, iommu@lists.linux.dev, Andrew Morton , christian.koenig@amd.com, Joerg Roedel , Marc Zyngier , Marek Szyprowski , Robin Murphy , Steven Price , Sumit Semwal , Suzuki K Poulose , Thomas Gleixner , Will Deacon , dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-media@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC PATCH v7 02/13] mm: Add an allocator for CoCo shared memory Message-ID: <20260923152124.GG1540250@ziepe.ca> References: <20260921144847.501151-1-aneesh.kumar@kernel.org> <20260921144847.501151-3-aneesh.kumar@kernel.org> <20260923130611.GF1540250@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 8CC341C000A X-Rspam-User: X-Stat-Signature: 1ygzeweygyrdg7deg4crs5am85wen8eg X-HE-Tag: 1790176886-712720 X-HE-Meta: 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 SfON1Sjv fThj1zYPmGI1x67ZZnsX0MktE3BSSxTzYkhpvMQEg+xJbz6XguqRGKkgjEvLvH5Y+Oz3UzlP9VxUu9Kr8wCm8RmNjgcGDi99h6opd4nPQGs8Y+2Zf1XQo8pw9LtS6eUGhA8zrlJjfH4TfexzkKuxdDE9a81MrHHVbxWLtswu7+eul7BimJpHIhyHPbRlLHmqJFKbPDmZqp48ZKOJLhahvuCZaX4QVyymowxglcWmy7ctUkWa8+i8GxcbM9EJtqzZrSP76BowEFqRLwejFIlwA+7/Dsse89zhrsD5P Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Sep 23, 2026 at 08:28:57PM +0530, Aneesh Kumar K.V wrote: > I'm also considering requiring the address passed to cc_make_shared() to > be in the linear map. This is currently required by both TDX and CCA, > while AMD SNP appears to support vmalloc addresses. The only user of > that vmalloc support is Hyper-V VMBus GPADL setup > (vmbus_establish_gpadl()). How should the generic CoCo shared-memory > allocator handle this? vmbus_establish_gpadl() is the the same wrong abstraction as the arch code. Get rid of it and use vmbus_establish_gpadl_caller_decrypted(): pdata->recv_buf = vzalloc(RECV_BUFFER_SIZE); if (!pdata->recv_buf) { ret = -ENOMEM; goto fail_free_ring; } ret = vmbus_establish_gpadl(channel, pdata->recv_buf, RECV_BUFFER_SIZE, &pdata->recv_gpadl); So you made an allocator that returns folios, now you just need to use that allocator to implement a kvzalloc wrapper. ARM can call vmap on decrypted memory with pgprot_decrypted(), right? Or maybe this can use vmbus_alloc_buffer(), it already does it. Jason