From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 4F7592F5474 for ; Tue, 30 Dec 2025 10:16:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767089799; cv=none; b=hNonCFznlX+CD35T0hJwgvExAYL9o5PsHUvIhBshSZfAUdE3KcduQhcuYtIx+Fn3x0i2kvOzTufmgQfAwS2J2zwwNx1aIjr4GnEQbI1isargCylT53jyGOCxpwqyNMToZlXC48DV9AjQM28OdtUR7zpp/svmnvfG+Qjw6u+MDKA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767089799; c=relaxed/simple; bh=ikTC7dMS0j+aOW64LriWXLGZXkKoO1gYmsQNBLOSYxo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=K5WVn/byuyGMFzdagdpC+n4dljNX88VNh9+1wloeYSVR4jPFE8lCQG0saHuipLxssqBDqE3SJiUatTcDsVjDfn1o4YAuO5/DWZi924uZQW/K6cRuaUX22INpAJmhnG9OeOKEfQyD8tbpJ+NQp6/Fy3wq06+yvXAGvovNLI3Cdi4= 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=hkow8Crk; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b=i4RoF07j; arc=none smtp.client-ip=170.10.129.124 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="hkow8Crk"; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b="i4RoF07j" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1767089796; 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=x4agnfRlmC5GgzX5Rd2z2Ldj0cW20QjlA2/E3WP30vs=; b=hkow8CrkVcd0/haLmVWfJaO3wPZn9EqzxaBVlJ22Lw+2Cy0U4N5nUG/4UNoaIb8u7vGrKn IzHUiIri+MWYH/WXRA58FyNs1m+on2dZyCcpOK59HX7QMvhv9vNtGPhdRGsRbJ8uYiqmes Xy7oLS8R2MjBgpjmQsgJMcMhecOFpJo= 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-259-v0Ze9bNKOnaxIky4zEVEWA-1; Tue, 30 Dec 2025 05:16:35 -0500 X-MC-Unique: v0Ze9bNKOnaxIky4zEVEWA-1 X-Mimecast-MFC-AGG-ID: v0Ze9bNKOnaxIky4zEVEWA_1767089794 Received: by mail-wm1-f70.google.com with SMTP id 5b1f17b1804b1-4792bd2c290so94172585e9.1 for ; Tue, 30 Dec 2025 02:16:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1767089794; x=1767694594; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=x4agnfRlmC5GgzX5Rd2z2Ldj0cW20QjlA2/E3WP30vs=; b=i4RoF07jbiZ9WBc7wJDhu//73X6pQxHb1DqtRSJZsT2eTKQTQoKTjUekZV7lUlwC86 SAi7JTMipA6B6VaLfUpwhfekUYYlnJzc3vCPjKlkBZRQ7BohHUQczZm+8Cbekj9X8i0r Pc5cZkU4g3uzIKARnxfAC0k6ID9y9ce5RoVd+aQ+dDYIqHAuK6U5tqTMjPnd7T1gQMyB rR1ZNAZ7DuuGa4AfQXOggLTDQ5LOTQvHnbCxELTxG7/CiVxsZc3O6qpp4gKsvYgaFE7f Q+bweP8e9W3rtBvqg0TTbNy+vjrUyx++7R94BPDv6S4+7dPMgkdUvMlmEuRFvTD2nTaT Xfyg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1767089794; x=1767694594; 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=x4agnfRlmC5GgzX5Rd2z2Ldj0cW20QjlA2/E3WP30vs=; b=GQ8Vc2n0sSAOIbRIrLDyZ+6zm9Ny/iGpevPI2FzuwewBAhTLvEpBbPF0jfcbeFQXTw 6i0er2AAoNDavNsfdtnG2pxGfZgb9jYoA7P/0Vo3ul9dXtv2myydZMrx83iiF4gGyMwB D8bscfA2bXNeT+i9xCLlDQuTvw4XMjRt2dyxWGxvm0w9VE+1tkUKXAy4q2eefquWJh6y mEtb3kvITtMYjoosEZrPUhQguBZCA88E6irx3Z5IaqVCa3LWDP9TwT4nP4a5/E23MLwg Q4CgIySksXNCn5Arh/f18A+WeE+orBOCG2SYu4CzFmzmWNRHWX6O57+bWpOL3fuTLUYE nC5A== X-Forwarded-Encrypted: i=1; AJvYcCW/UYj/beBexxD/D731WojSP8UIgAq/fbxUhNhinHr8syPvogefteXDaKJspkZcbLBcXSuKR66avr8=@vger.kernel.org X-Gm-Message-State: AOJu0YykHH3j5egCZR8M1JtEeNyxC6RJA278lgxCcgYf7s2VaOGdA2e9 e3q7R5FtcIOkYcU+w9aBW2Ylz11pfENK4U5am+wXt7csOlDOEKJgLYvnnzBq7atM8C6KK81VxM2 8j50s3DWHVD8VcSSHEGbRhGyl64PE1lb87+DMEHEtCXFtHB5iQqxGvGpyA4XHpQ== X-Gm-Gg: AY/fxX7IJhEKK0q1n6md4SrAi6ADtjWy7wazmofNFmRSN/xvbUlgrTsqaiHwxn7114c jrpdE/wHmVJUcdpLcnww20tXINpuABF6gy2SXKY5Ug5buwYDt+5ci/EiCl7t5jIkLDZnWs9LhEr 9dZvTT3/o8553Ld1fqW74iihFoi+RBqC+beILMRGFSQ0TQfXGmpaSTlU7RzyhUki6FsPOU60UkZ gA8Xm+j+bJKht/CTrhYDXB4OZGdk8k68FXF+U1RWblYizXpFycNHQ4lbBfT10qlzHbZI3A35wiv BpXAQz0p7m4v5ULN3yizQ2DCUxGdoI0Tg2ZhKUk7qbOhyZgOqndFakdgAqtOoGz795JfaYpZcm5 0Vo+SrKPG5O9GFbwvSoM4IPbNh5pKVnJBPw== X-Received: by 2002:a05:600c:8b8c:b0:477:af07:dd1c with SMTP id 5b1f17b1804b1-47d195aaf01mr352317535e9.35.1767089793799; Tue, 30 Dec 2025 02:16:33 -0800 (PST) X-Google-Smtp-Source: AGHT+IE/8/udlvjg5mJuYpI0a3oxpEJUtwKIPq+rFtOrgdem6Ktq8tTHyeQzy9WGlYRf+5N+zum/GQ== X-Received: by 2002:a05:600c:8b8c:b0:477:af07:dd1c with SMTP id 5b1f17b1804b1-47d195aaf01mr352317095e9.35.1767089793385; Tue, 30 Dec 2025 02:16:33 -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 5b1f17b1804b1-47be27b28a7sm638896415e9.12.2025.12.30.02.16.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 30 Dec 2025 02:16:33 -0800 (PST) Date: Tue, 30 Dec 2025 05:16:29 -0500 From: "Michael S. Tsirkin" To: linux-kernel@vger.kernel.org Cc: Cong Wang , Jonathan Corbet , Olivia Mackall , Herbert Xu , Jason Wang , Paolo Bonzini , Stefan Hajnoczi , Eugenio =?utf-8?B?UMOpcmV6?= , "James E.J. Bottomley" , "Martin K. Petersen" , Gerd Hoffmann , Xuan Zhuo , Marek Szyprowski , Robin Murphy , Stefano Garzarella , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Petr Tesarik , Leon Romanovsky , Jason Gunthorpe , 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: [PATCH RFC 13/13] vsock/virtio: reorder fields to reduce struct padding Message-ID: References: Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Mailer: git-send-email 2.27.0.106.g8ac3dc51b1 X-Mutt-Fcc: =sent Reorder struct virtio_vsock fields to place the DMA buffer (event_list) last. This eliminates the need for __dma_from_device_aligned_end padding after the DMA buffer, since struct tail padding naturally protects it, making the struct a bit smaller. Size reduction estimation when ARCH_DMA_MINALIGN=128: - event_list is 32 bytes - removing _end saves up to 128-32=96 bytes padding to align next field Signed-off-by: Michael S. Tsirkin --- net/vmw_vsock/virtio_transport.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c index f1589db5d190..2e34581f1143 100644 --- a/net/vmw_vsock/virtio_transport.c +++ b/net/vmw_vsock/virtio_transport.c @@ -60,10 +60,7 @@ struct virtio_vsock { */ struct mutex event_lock; bool event_run; - __dma_from_device_aligned_begin - struct virtio_vsock_event event_list[8]; - __dma_from_device_aligned_end u32 guest_cid; bool seqpacket_allow; @@ -77,6 +74,10 @@ struct virtio_vsock { */ struct scatterlist *out_sgs[MAX_SKB_FRAGS + 1]; struct scatterlist out_bufs[MAX_SKB_FRAGS + 1]; + + /* DMA buffer - must be last, aligned for non-cache-coherent DMA */ + __dma_from_device_aligned_begin + struct virtio_vsock_event event_list[8]; }; static u32 virtio_transport_get_local_cid(void) -- MST