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[82.53.135.154]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4815f15b946sm6204391f8f.0.2026.08.14.00.59.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 14 Aug 2026 00:59:02 -0700 (PDT) Date: Fri, 14 Aug 2026 09:58:58 +0200 From: Stefano Garzarella To: Jia Jia Cc: Stefan Hajnoczi , "Michael S . Tsirkin" , Jason Wang , Eugenio =?utf-8?B?UMOpcmV6?= , kvm@vger.kernel.org, virtualization@lists.linux.dev, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 2/3] vhost/vsock: discard IOTLB when ACCESS_PLATFORM is cleared Message-ID: References: <20260814072903.124991-1-physicalmtea@gmail.com> <20260814072903.124991-3-physicalmtea@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20260814072903.124991-3-physicalmtea@gmail.com> On Fri, Aug 14, 2026 at 03:29:02PM +0800, Jia Jia wrote: >vhost_vsock_set_features() leaves the device IOTLB attached when >userspace clears VIRTIO_F_ACCESS_PLATFORM. Descriptors can therefore >continue to use translations installed before the feature change, >including HVAs made stale by a later memory table update. > >Use the common vhost helper to detach the device IOTLB before >acknowledging a feature mask without ACCESS_PLATFORM. The helper clears >each virtqueue's IOTLB pointer and metadata cache under its mutex, then >frees the old IOTLB after all virtqueues have dropped their references. > >Fixes: e13a6915a03f ("vhost/vsock: add IOTLB API support") >Suggested-by: Michael S. Tsirkin >Signed-off-by: Jia Jia >--- > drivers/vhost/vsock.c | 4 ++++ > 1 file changed, 4 insertions(+) > >diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c >index 9aaab6bb8061..b69c260eaeff 100644 >--- a/drivers/vhost/vsock.c >+++ b/drivers/vhost/vsock.c >@@ -863,7 +863,11 @@ static int vhost_vsock_set_features(struct vhost_vsock *vsock, u64 features) > if ((features & (1 << VHOST_F_LOG_ALL)) && > !vhost_log_access_ok(&vsock->dev)) { > goto err; > } > >+ if (!(features & (1ULL << VIRTIO_F_ACCESS_PLATFORM)) && >+ vsock->dev.iotlb) >+ vhost_clear_device_iotlb(&vsock->dev); >+ Why checking the feature again instead of adding an `else if` in the already existing check? I mean this... > if ((features & (1ULL << VIRTIO_F_ACCESS_PLATFORM))) { > if (vhost_init_device_iotlb(&vsock->dev)) > goto err; } else if (vsock->dev.iotlb) { vhost_clear_device_iotlb(&vsock->dev); } >-- 2.34.1 >