From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 671CB3D3307 for ; Thu, 8 Jan 2026 14:08:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767881283; cv=none; b=bni9rSBANEi0sGolXIAnCiqc5EgCNsfeouIRhSRHP1vXn8Nm1AKBrzdBdKblXrPFT8an6sUh0DDD1IpxhU7ph1tPcz2pCqinw44DOggYMqo0Xzt2zGFRyjxWko/IjPRJLGLmkxwyoo2YH6jvG2Es9QrTQrg+bevYql8E3tD1EMI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767881283; c=relaxed/simple; bh=KaqiKIrSwJ+ZnBNZThkRID6OHOTJLOwB/Uij0QQJV1Q=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: In-Reply-To:Content-Type:Content-Disposition; b=bwIcCR6IfpqmWxeUiOlzW8wuFZhVvn0D4dvNgW/BcFS+t0DatQGidntbjf5jiXDrEQnjzZ7W9za6gXN1pk4seStWzTyHK57JbfMydkxBYdgjsqLijcDxU2DxZAaA0Ym7SqbX1hiZsaYz+8kCU8JsUPC9uU9gzBkzPlhrQRSv/LA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=DC+z1wRw; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="DC+z1wRw" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1767881280; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=o3dV3iJKWcALTHlfMC1TmWQCBk2jAXP+lliSQZRypr4=; b=DC+z1wRwPZkoDB0V0nMq+zA2bs5MIJYw6bINgXSFjswyryJ2mTCrLatbKQcGDywcl4AY4c eKHEl1A+UnE4VMdCeTw7WV+p9T6ZhhZ4lswneW3nNG770YRFTVy5tkuXUu05TSgrEMyhMM 1paeVsIad1KhDgwvR2ZRh4+89SfFcdc= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-460-7lWRbx37PMy4u0A8OZM7aA-1; Thu, 08 Jan 2026 09:07:59 -0500 X-MC-Unique: 7lWRbx37PMy4u0A8OZM7aA-1 X-Mimecast-MFC-AGG-ID: 7lWRbx37PMy4u0A8OZM7aA_1767881278 Received: by mail-wm1-f70.google.com with SMTP id 5b1f17b1804b1-47d1622509eso20961455e9.3 for ; Thu, 08 Jan 2026 06:07:59 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1767881278; x=1768486078; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=o3dV3iJKWcALTHlfMC1TmWQCBk2jAXP+lliSQZRypr4=; b=mURnczztt8GrY4kJA68GvhrXRgJBN7ydIqKZ+hfjk93xgBe7+GZVmwKfjb7LnO6Oe5 +UhKGV4P1Ovsd6RHy2x3yyWirq1ysalUVf7qH9InYgCV8yQ8y9f37LGD/k4g2Jsgz0vk WPpxgAEF9SEuYGUbs8/jpafFYMo8Pm4QlkXczxS7hLLqevGjJea99PQwmGUscY3TTReK uSR/dUFYWjjooaJc5EO8mENAoEUoz/52viVXZfoWqJRD0qg5O0CVh1U89NbVITMA5WnI qaiusHIC8o0+H1syeVAqyqmaWuWQtrKxBCR5dfOeEIFPFbbwOJk74FLWezr2IE4A5vAj jfyw== X-Forwarded-Encrypted: i=1; AJvYcCVpFkmgSaRJcPdo3NIbPnVYSPI4nVtjwDopDhzVYYAB5Dl/flh8u5RMDeHJdPC0xPE4NGUbgCybdEy2/SIykQ==@lists.linux.dev X-Gm-Message-State: AOJu0Yyz7HSkeylTtWtqIG1L2f9VYxTpe5FoxU54NOpqpEhtgVLU9NVD HHxMKMjiyc+PF9qLX7UpI06FpNhq+pskpLiJAMu4poHQmshCim3caFdF7uf18NTL7X+Xj+Gmd0m R4qV3t+CldZaAYEpRbZsAi/svLb1cu+0gR5WfGVbd1OSDSE082XB7gDX+XR44dpS4DHeo X-Gm-Gg: AY/fxX6RdcawhwY+EP/n90IE8z8B6nQNdqBf5syK85s52NIDuMqYFKmAAulEgnzHMNS uhN4x8GRCtc+/jTk3udBNN2SoZbqEyoBRdOoecmSKdTL+RCelJVO8PdqV1Co8vRs3xPmDxZFviz N/gTj3ePfQJxGu9mqpAyVfXtNmrHXL68M8WBBLgkmXtT423uqzHjKPHCFuY9qQExtQrZRbBj6Gq K4VqzlJkbj9wikXZpjFGgUjSigFnhzYaoBW2R3AJbHcG5zypQ+HO82+W7jJabKm/p7GqdmkDt/b kHFQZwlg4rhYuKK714oERKmkOmVsATo/sHw+Ceq2f90OFiZd0GULv/+GH0yFt0pMjw6FCz1yOBd 2csjkiMAkTsYue+2YZ6rVw/uRF1potxwSQQ== X-Received: by 2002:a05:600c:1385:b0:47d:4fbe:e6d2 with SMTP id 5b1f17b1804b1-47d84b2cd6dmr72553025e9.12.1767881277891; Thu, 08 Jan 2026 06:07:57 -0800 (PST) X-Google-Smtp-Source: AGHT+IHRCfp6entO3V/BR31Far6TJcGMp3EAPQ3dAY6QbDFNrKF2+2e3Jhs1Nmifuq8757Npv4Rh0Q== X-Received: by 2002:a05:600c:1385:b0:47d:4fbe:e6d2 with SMTP id 5b1f17b1804b1-47d84b2cd6dmr72552445e9.12.1767881277386; Thu, 08 Jan 2026 06:07:57 -0800 (PST) Received: from redhat.com (IGLD-80-230-31-118.inter.net.il. [80.230.31.118]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-47d7f68f4ddsm160806445e9.2.2026.01.08.06.07.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 08 Jan 2026 06:07:56 -0800 (PST) Date: Thu, 8 Jan 2026 09:07:53 -0500 From: "Michael S. Tsirkin" To: Stefano Garzarella Cc: linux-kernel@vger.kernel.org, Cong Wang , Jonathan Corbet , Olivia Mackall , Herbert Xu , Jason Wang , Paolo Bonzini , Stefan Hajnoczi , Eugenio =?iso-8859-1?Q?P=E9rez?= , "James E.J. Bottomley" , "Martin K. Petersen" , Gerd Hoffmann , Xuan Zhuo , Marek Szyprowski , Robin Murphy , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Petr Tesarik , Leon Romanovsky , Jason Gunthorpe , Bartosz Golaszewski , linux-doc@vger.kernel.org, linux-crypto@vger.kernel.org, virtualization@lists.linux.dev, linux-scsi@vger.kernel.org, iommu@lists.linux.dev, kvm@vger.kernel.org, netdev@vger.kernel.org Subject: Re: [PATCH v2 07/15] vsock/virtio: fix DMA alignment for event_list Message-ID: <20260108090639-mutt-send-email-mst@kernel.org> References: Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: gPJgF4822W4hlNgNpNGBG4A5ka8kizdQAFXYKh79ge4_1767881278 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Thu, Jan 08, 2026 at 03:04:07PM +0100, Stefano Garzarella wrote: > On Mon, Jan 05, 2026 at 03:23:17AM -0500, Michael S. Tsirkin wrote: > > On non-cache-coherent platforms, when a structure contains a buffer > > used for DMA alongside fields that the CPU writes to, cacheline sharing > > can cause data corruption. > > > > The event_list array is used for DMA_FROM_DEVICE operations via > > virtqueue_add_inbuf(). The adjacent event_run and guest_cid fields are > > written by the CPU while the buffer is available, so mapped for the > > device. If these share cachelines with event_list, CPU writes can > > corrupt DMA data. > > > > Add __dma_from_device_group_begin()/end() annotations to ensure event_list > > is isolated in its own cachelines. > > > > Signed-off-by: Michael S. Tsirkin > > --- > > net/vmw_vsock/virtio_transport.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c > > index 8c867023a2e5..bb94baadfd8b 100644 > > --- a/net/vmw_vsock/virtio_transport.c > > +++ b/net/vmw_vsock/virtio_transport.c > > @@ -17,6 +17,7 @@ > > #include > > #include > > #include > > +#include > > #include > > #include > > #include > > @@ -59,8 +60,9 @@ struct virtio_vsock { > > */ > > struct mutex event_lock; > > bool event_run; > > + __dma_from_device_group_begin(); > > struct virtio_vsock_event event_list[8]; > > - > > + __dma_from_device_group_end(); > > Can we keep the blank line before `guest_cid` so that the comment before > this section makes sense? (regarding the lock required to access these > fields) > > Thanks, > Stefano A follow up patch re-introduces it, so I don't think it matters? > > u32 guest_cid; > > bool seqpacket_allow; > > > > -- > > MST > >