From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sender4-pp-f112.zoho.com (sender4-pp-f112.zoho.com [136.143.188.112]) (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 0C9191D5AB9 for ; Thu, 20 Feb 2025 03:20:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=pass smtp.client-ip=136.143.188.112 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740021644; cv=pass; b=FsecERqFlVsEhGNwwyKYA+uhSzGGMbcxWBct7odhcNQK0veSpWPJAyGveNvErHv0LW34H3+gUajILjZOrgPtqMEeHzrYM4agK9ctNz1zN3dgbcp+B4mmUT4ZTAiofUUUDyHr9zO9eorZxBCZu3E3UJxWnANs+ONo/YaNdC0rp9o= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740021644; c=relaxed/simple; bh=FFRqQD38fqHqNNra69YMR0ZnN6Yry8+yeUHE07ibhpE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=I6vSdcQmdio+Y+ZgnbDf78IRLtcBwD0op5t7zjy1BZLd6IFBf6hl/35J3ZvIgbbenfmUOTQXfrw2TumXh/i99Jkxv2YT7OnhGdFS/we4IPiPwL+ZY2pfunrej4RTWLUZsvv5O6Lnt3Hc8erbwIF1bRGjyfS9IGX59v/WcLELDKk= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com; spf=pass smtp.mailfrom=collabora.com; dkim=pass (1024-bit key) header.d=collabora.com header.i=dmitry.osipenko@collabora.com header.b=Td0u68vs; arc=pass smtp.client-ip=136.143.188.112 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=collabora.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=collabora.com header.i=dmitry.osipenko@collabora.com header.b="Td0u68vs" ARC-Seal: i=1; a=rsa-sha256; t=1740021622; cv=none; d=zohomail.com; s=zohoarc; b=n5Hb6jI2YOgJvoMOM5AWZuWfhIARag7BXle+ouX0gV5c6s51QOVvsw3NtDIsCUchYAHjQFel8rTKqYn3QLRVfKENIl48sp/BlQ9JTT4Y0U3iRehjoZPP+VfSglEBa9AU9H83jPpfKk/yyXcg0YP74XQChTd+7CCrhKHBej1rl3Y= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1740021622; h=Content-Type:Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:MIME-Version:Message-ID:References:Subject:Subject:To:To:Message-Id:Reply-To; bh=goELxg5KRmIAVFiFo0WsH6I8YxpNZKoXy3YbksbDQ5Q=; b=chzILRRNTBRD5OlJP++5hnxNeiLgiK2ci+77QBz+S7LC73NVuJwAkpeUK7nTQgmg7sRaqrsKDVNZYksvyMcKBmfqvo63GpZ+ub//mRFd3xQIn32dJ2DqJ9aV0sIEejuy09qwaLFykOCPhjBSskTONO3qfNnTq2hZDRztTbGtf5g= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass header.i=collabora.com; spf=pass smtp.mailfrom=dmitry.osipenko@collabora.com; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1740021622; s=zohomail; d=collabora.com; i=dmitry.osipenko@collabora.com; h=Message-ID:Date:Date:MIME-Version:Subject:Subject:To:To:Cc:Cc:References:From:From:In-Reply-To:Content-Type:Content-Transfer-Encoding:Message-Id:Reply-To; bh=goELxg5KRmIAVFiFo0WsH6I8YxpNZKoXy3YbksbDQ5Q=; b=Td0u68vsLAKi/a2k0vTvbI3wCZO97WtRkuQMBG5u46ytyqT0OMcsqLR7WtrNEI9/ AP1r7MgliczWKsJ2ZsXvqLuiwbqYrfOH9qZ1GgcC6mmGDIpg1gRtrADszhkCt+CCV4B mmHCq2oqfNEYe53OGEtgBTW953lSrKsEy2lxE/Ao= Received: by mx.zohomail.com with SMTPS id 1740021619797826.5630263636273; Wed, 19 Feb 2025 19:20:19 -0800 (PST) Message-ID: <1f9a86a5-97d6-41d5-9a30-0422fc9ec137@collabora.com> Date: Thu, 20 Feb 2025 06:20:13 +0300 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC v2 4/5] virtio-mmio: read shm region page size To: Sergio Lopez , "Michael S. Tsirkin" , Daniel Verkamp , Jason Wang , Xuan Zhuo , =?UTF-8?Q?Eugenio_P=C3=A9rez?= , David Airlie , Gerd Hoffmann , Gurchetan Singh , Chia-I Wu , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Simona Vetter , Rob Clark , fnkl.kernel@gmail.com Cc: virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org References: <20250214-virtio-shm-page-size-v2-0-aa1619e6908b@redhat.com> <20250214-virtio-shm-page-size-v2-4-aa1619e6908b@redhat.com> From: Dmitry Osipenko Content-Language: en-US In-Reply-To: <20250214-virtio-shm-page-size-v2-4-aa1619e6908b@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-ZohoMailClient: External On 2/14/25 18:16, Sergio Lopez wrote: > Use the newly introduced SHM_PAGE_SHIFT register to read the page shift > for the shared memory region, derive the page size from it and store the > resulting value into virtio_shm_region. > > Signed-off-by: Sergio Lopez > --- > drivers/virtio/virtio_mmio.c | 11 ++++++++++- > include/uapi/linux/virtio_mmio.h | 3 +++ > 2 files changed, 13 insertions(+), 1 deletion(-) > > diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c > index 1f594b626d7a7734e8ec58766737a118c26bad94..0f892770739ea84b3e7be5615332773049b10ab1 100644 > --- a/drivers/virtio/virtio_mmio.c > +++ b/drivers/virtio/virtio_mmio.c > @@ -537,6 +537,7 @@ static bool vm_get_shm_region(struct virtio_device *vdev, > struct virtio_shm_region *region, u8 id) > { > struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev); > + u8 page_shift = 0; > u64 len, addr; > > /* Select the region we're interested in */ > @@ -560,7 +561,15 @@ static bool vm_get_shm_region(struct virtio_device *vdev, > > region->addr = addr; > > - region->page_size = 4096; > + /* If supported by the device transport, read the region page size. > + * The page_shift variable is initialized to zero above, so if this > + * feature isn't supported it will result in a page_size of 4096, a > + * default safe value. > + */ > + if (__virtio_test_bit(vdev, VIRTIO_F_SHM_PAGE_SIZE)) > + page_shift = (u8) readl(vm_dev->base + VIRTIO_MMIO_SHM_PAGE_SHIFT); > + > + region->page_size = 1 << (page_shift + 12); > > return true; > } > diff --git a/include/uapi/linux/virtio_mmio.h b/include/uapi/linux/virtio_mmio.h > index 0650f91bea6c70f935764070d825d181a2379afb..43348be30eff90ee228b6490b9d3c35ba4c50aa5 100644 > --- a/include/uapi/linux/virtio_mmio.h > +++ b/include/uapi/linux/virtio_mmio.h > @@ -133,6 +133,9 @@ > #define VIRTIO_MMIO_SHM_BASE_LOW 0x0b8 > #define VIRTIO_MMIO_SHM_BASE_HIGH 0x0bc > > +/* Shared memory region page shift */ > +#define VIRTIO_MMIO_SHM_PAGE_SHIFT 0x0c4 What's the logic behind choosing 0x0c4, why not 0x0c0? -- Best regards, Dmitry