From patchwork Tue Oct 6 14:29:25 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin O'Connor X-Patchwork-Id: 526788 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 5425C140D71 for ; Wed, 7 Oct 2015 01:31:05 +1100 (AEDT) Received: from localhost ([::1]:52034 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZjTGh-0004Jn-6o for incoming@patchwork.ozlabs.org; Tue, 06 Oct 2015 10:31:03 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38869) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZjTFD-0003sO-8O for qemu-devel@nongnu.org; Tue, 06 Oct 2015 10:29:32 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZjTF9-00012c-VJ for qemu-devel@nongnu.org; Tue, 06 Oct 2015 10:29:31 -0400 Received: from mail-qk0-f178.google.com ([209.85.220.178]:33697) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZjTF9-00012I-Ry for qemu-devel@nongnu.org; Tue, 06 Oct 2015 10:29:27 -0400 Received: by qkas79 with SMTP id s79so86283732qka.0 for ; Tue, 06 Oct 2015 07:29:27 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-type:content-disposition:in-reply-to :user-agent; bh=xFmtE+xyqi+FCCqozPNXq+UGrx6mhTFbNgtvYBh6If0=; b=b7ET5Xb+WuKMPvU7GcoqHqbv78S355YlPfVEAINBQ8QUU5IKdkzBpA1nU01M0gzs1I iSuLmulBhJJn++7SkhrBe5ewv5FD4xitELxa6F3l/NbQBChZABMbQcivuOe+OxD8T17x 6TXKcjl8CIh5zT6hkX9fl5RClipg4nr+dVbrVP8nV8XX8MwHZQyMqunxHcVC5cH15g2l hg2fERktKEk8SWc8tRLkyo0x37yM8XqXgflfMmdjXoHcgOqBrqqh5I8AjcQjiQnP9g+0 BVqm1SWG7oapmfV63OKM4+bQjua9ZlaLwopYTo05oJBp2rT/SVNMf/THRTftl6dJyvhB khUg== X-Gm-Message-State: ALoCoQk8dlvmBeGO5BrzF2HkrmXxqCRFnyVhUiYHqO11yBF6Ib/tPNJoZnz4TIYI+X/grziDM7Eo X-Received: by 10.55.215.156 with SMTP id t28mr10223492qkt.68.1444141767220; Tue, 06 Oct 2015 07:29:27 -0700 (PDT) Received: from localhost (209-122-232-221.c3-0.avec-ubr1.nyr-avec.ny.cable.rcn.com. [209.122.232.221]) by smtp.gmail.com with ESMTPSA id i21sm10286911qkh.48.2015.10.06.07.29.26 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 06 Oct 2015 07:29:26 -0700 (PDT) Date: Tue, 6 Oct 2015 10:29:25 -0400 From: Kevin O'Connor To: Laszlo Ersek , Marc =?iso-8859-1?Q?Mar=ED?= Message-ID: <20151006142925.GB6361@morn.lan> References: <1444089115-28710-1-git-send-email-kevin@koconnor.net> <5613788A.1070409@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <5613788A.1070409@redhat.com> User-Agent: Mutt/1.5.23 (2014-03-12) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.85.220.178 Cc: Stefan Hajnoczi , qemu-devel@nongnu.org Subject: Re: [Qemu-devel] [PATCHv2] fw_cfg: Define a static signature to be returned on DMA port reads X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org On Tue, Oct 06, 2015 at 09:30:18AM +0200, Laszlo Ersek wrote: > On 10/06/15 01:51, Kevin O'Connor wrote: > > Return a static signature ("QEMU CFG") if the guest does a read to the > > DMA address io register. > > > > Signed-off-by: Kevin O'Connor > > --- > > > > Marc, if you decide to respin your fw_cfg series, I've updated the dma > > signature patch. This addresses the comments from Stefan, and I hope > > it addresses the comments from Laszlo. > > Thank you -- I didn't know about extract64(). > > The patch looks good to me, but I think the QEMU coding style requries > /* ... */ comments, and forbids //. I always forget about that one. Marc, if you do respin the series I updated the patch below. -Kevin commit 02a449ece95da00fa64a9c704555c6afa8e03579 Author: Kevin O'Connor Date: Thu Oct 1 14:16:59 2015 +0200 fw_cfg: Define a static signature to be returned on DMA port reads Return a static signature ("QEMU CFG") if the guest does a read to the DMA address io register. Reviewed-by: Stefan Hajnoczi Signed-off-by: Kevin O'Connor Reviewed-by: Laszlo Ersek diff --git a/docs/specs/fw_cfg.txt b/docs/specs/fw_cfg.txt index 2d6b2da..cbdce7d 100644 --- a/docs/specs/fw_cfg.txt +++ b/docs/specs/fw_cfg.txt @@ -93,6 +93,9 @@ by selecting the "signature" item using key 0x0000 (FW_CFG_SIGNATURE), and reading four bytes from the data register. If the fw_cfg device is present, the four bytes read will contain the characters "QEMU". +If the DMA interface is available, then reading the DMA Address +Register returns 0x51454d5520434647 ("QEMU CFG" in big-endian format). + === Revision / feature bitmap (Key 0x0001, FW_CFG_ID) === A 32-bit little-endian unsigned int, this item is used to check for enabled diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c index 59933b3..5098bfc 100644 --- a/hw/nvram/fw_cfg.c +++ b/hw/nvram/fw_cfg.c @@ -53,6 +53,8 @@ #define FW_CFG_DMA_CTL_SKIP 0x04 #define FW_CFG_DMA_CTL_SELECT 0x08 +#define FW_CFG_DMA_SIGNATURE 0x51454d5520434647 /* "QEMU CFG" */ + typedef struct FWCfgEntry { uint32_t len; uint8_t *data; @@ -393,6 +395,13 @@ static void fw_cfg_dma_transfer(FWCfgState *s) trace_fw_cfg_read(s, 0); } +static uint64_t fw_cfg_dma_mem_read(void *opaque, hwaddr addr, + unsigned size) +{ + /* Return a signature value (and handle various read sizes) */ + return extract64(FW_CFG_DMA_SIGNATURE, (8 - addr - size) * 8, size * 8); +} + static void fw_cfg_dma_mem_write(void *opaque, hwaddr addr, uint64_t value, unsigned size) { @@ -416,8 +425,8 @@ static void fw_cfg_dma_mem_write(void *opaque, hwaddr addr, static bool fw_cfg_dma_mem_valid(void *opaque, hwaddr addr, unsigned size, bool is_write) { - return is_write && ((size == 4 && (addr == 0 || addr == 4)) || - (size == 8 && addr == 0)); + return !is_write || ((size == 4 && (addr == 0 || addr == 4)) || + (size == 8 && addr == 0)); } static bool fw_cfg_data_mem_valid(void *opaque, hwaddr addr, @@ -488,6 +497,7 @@ static const MemoryRegionOps fw_cfg_comb_mem_ops = { }; static const MemoryRegionOps fw_cfg_dma_mem_ops = { + .read = fw_cfg_dma_mem_read, .write = fw_cfg_dma_mem_write, .endianness = DEVICE_BIG_ENDIAN, .valid.accepts = fw_cfg_dma_mem_valid,