From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 0C109CCA470 for ; Fri, 3 Oct 2025 08:38:45 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.1136429.1473002 (Exim 4.92) (envelope-from ) id 1v4bJ9-00029D-2c; Fri, 03 Oct 2025 08:38:31 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 1136429.1473002; Fri, 03 Oct 2025 08:38:31 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1v4bJ8-000296-W2; Fri, 03 Oct 2025 08:38:30 +0000 Received: by outflank-mailman (input) for mailman id 1136429; Fri, 03 Oct 2025 08:38:30 +0000 Received: from se1-gles-sth1-in.inumbo.com ([159.253.27.254] helo=se1-gles-sth1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1v4bJ7-000290-W7 for xen-devel@lists.xenproject.org; Fri, 03 Oct 2025 08:38:29 +0000 Received: from mail-ed1-x52a.google.com (mail-ed1-x52a.google.com [2a00:1450:4864:20::52a]) by se1-gles-sth1.inumbo.com (Halon) with ESMTPS id 55f062c9-a034-11f0-9d14-b5c5bf9af7f9; Fri, 03 Oct 2025 10:38:29 +0200 (CEST) Received: by mail-ed1-x52a.google.com with SMTP id 4fb4d7f45d1cf-62fc28843ecso2919567a12.1 for ; Fri, 03 Oct 2025 01:38:29 -0700 (PDT) Received: from [192.168.1.5] (user-109-243-67-38.play-internet.pl. [109.243.67.38]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-6376b3ab4b0sm3541664a12.5.2025.10.03.01.38.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 03 Oct 2025 01:38:27 -0700 (PDT) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 55f062c9-a034-11f0-9d14-b5c5bf9af7f9 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1759480708; x=1760085508; darn=lists.xenproject.org; h=in-reply-to:from:content-language:references:cc:to:subject :user-agent:mime-version:date:message-id:from:to:cc:subject:date :message-id:reply-to; bh=Hl6DKbhYmaWddgFsA96ck65hAIkdKmRmctwiDKkWjns=; b=epshcqVPvvFQuxLRwfL7lETDJl1AH9VCrjJhlIhNrATtkL/KMmrJe5AeaEMgi/fwVj 1Yi3eUgCaYnX+odxf1HUeAhVDPDjB2a93sQldbRdf3AUySAY50eEriDNMUKMdbrfkTcR bW5M6NqKyT8NkuMCSHyyf98/85CNodg/ae6p/HirkeZn2Wgho6Hjufsd70nna+ouh7Hq VGSRD2kL3iTdl3YMVveGS678ile0shZ4Lj6NxEDQdZYoW3Zo0CeQ4lY5+WUNC3ihkRfT nxbpwZQshN42VV5pBHOLDBF/4EqGgr5gOrreorEiv8V5dSXZKN7eF5lQuiKOWkh+HudA VyYw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1759480708; x=1760085508; h=in-reply-to:from:content-language:references:cc:to:subject :user-agent:mime-version:date:message-id:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to; bh=Hl6DKbhYmaWddgFsA96ck65hAIkdKmRmctwiDKkWjns=; b=EZr8cX9UunR+YLXrN8Xpw60lucvlgiTUFBDfb3xzWsx0V4QLzNKEafqV7HcnLXtj33 WEZUMXGj+iwd5m0/uNwoOnqQA7JcvPiMicenHBXPALVk7jptudDY762n2ZicxCfiX/u3 rFXel2h/oxKZTgaT4JE6IeKY0/YwkImkNVluSTc1vbHMb3gmi/4oUMe6rSyqlGv7oKAq WVayzBb0s8Gh52KGe3NiBh5yWUCHBKGq8X3cMX1KC53ojaOLYCfG4IQ89zPa1SR5sDsY hUolf0Eu+kIJBGapdm/VARmrJK2ZFK5YvCBuKawQ9x6vIiNrLV/Be6Kk3Ec4xT0LHWHS L+eg== X-Gm-Message-State: AOJu0YwLx3i5oPY474yYC6iHlU3SWjT0jOPipEP+IpKn8V5W155J1wRl 9EGnJjvvn7r8MAY1eER++MuE4LC3ewvo3fnD4NkGvEW5VmxfbifEN74Qu+7hsQ== X-Gm-Gg: ASbGncvCg85sPsb4yXxCKLyeSTjoUnHGG62gOfmvv5mcBuZ1Uuc7mj0T7ykAg6u0dJz tfxm6iKJTNEpjPpK7FOPYTbhw0tlWDCrUD8DHaediWrmxLbg6IySsSDOIqi7zxqesJ/tl+UW2nt 9+7489derCl9ZRDIjeSva6U+qyYxO9fX3VHOSvk0fY9DqenFbSMhZei181GK6vrwC1W50pB8GDU P2LG35i0ne+WGAWyvbvCxIWoVHmvvDEevJxbnnIdJfoMgIaIwGBL4vqTzvQsa7/40T9N6obJ9kl CiZtCSXfwURAFo7QGUszWSD77Wp+C93aXu8OESsUI1DMgWgHRX+4jnJOf1NsB3UWJ+e+NZhYhRy 31TrEEwL4FNSjy0coHwthvOV2NUpjxPDHghdjLdxHjAmFTVgETZRcZqUYVW2d8sG8l90r2e7+5U 9lnkrpqOcgvCDQD5wUQ22up6nPLkA+7AHnPDQ= X-Google-Smtp-Source: AGHT+IGZEuldA8S/udifmtpZVgfUTugv0952Lll0Nxqs88YhxznHjYM08cBEPRl/dDgBglOg6hWLCw== X-Received: by 2002:a05:6402:3585:b0:638:3f72:125a with SMTP id 4fb4d7f45d1cf-639348d76b4mr2171290a12.14.1759480708220; Fri, 03 Oct 2025 01:38:28 -0700 (PDT) Content-Type: multipart/alternative; boundary="------------zyZ48vpMNzFA60oUHSnRUi4M" Message-ID: Date: Fri, 3 Oct 2025 10:38:27 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH for-4.21] x86/hvm: fix reading from 0xe9 IO port if port E9 hack is active To: =?UTF-8?Q?Roger_Pau_Monn=C3=A9?= , Andrew Cooper Cc: xen-devel@lists.xenproject.org, Jan Beulich References: <20251002102200.15548-1-roger.pau@citrix.com> <1b4bcb40-d62b-47b5-847f-b6e16906f52e@citrix.com> Content-Language: en-US From: Oleksii Kurochko In-Reply-To: This is a multi-part message in MIME format. --------------zyZ48vpMNzFA60oUHSnRUi4M Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 10/2/25 3:38 PM, Roger Pau Monné wrote: > On Thu, Oct 02, 2025 at 11:37:36AM +0100, Andrew Cooper wrote: >> On 02/10/2025 11:22 am, Roger Pau Monne wrote: >>> Reading from the E9 port if the emergency console is active should return >>> 0xe9 according to the documentation from Bochs: >>> >>> https://bochs.sourceforge.io/doc/docbook/user/bochsrc.html >>> >>> See `port_e9_hack` section description. >>> >>> Fix Xen so it also returns the port address. OSes can use it to detect >>> whether the emergency console is available or not. >>> >>> Fixes: d1bd157fbc9b ("Big merge the HVM full-virtualisation abstractions.") >>> Signed-off-by: Roger Pau Monné >> Reviewed-by: Andrew Cooper >> >> That's been wrong for rather a long time.  How did you find it? > I came across the documentation above and I didn't remember Xen > returning any value for reads, which sadly was indeed true. > > This was because I had the intention to suggest Alejandro to (also?) use > the port 0xe9 hack for printing from XTF, which should work for both > Xen and QEMU. > >> CC-ing Oleksii as you've tagged this for 4.21. > I was told that bugfixes didn't need a release-ack until hard code > freeze, which is the 31st of October? I meant until the start of the hard code freeze, which is on October 4. So there is no need for a release-ack for this patch. Thanks. ~ Oleksii --------------zyZ48vpMNzFA60oUHSnRUi4M Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 8bit


On 10/2/25 3:38 PM, Roger Pau Monné wrote:
On Thu, Oct 02, 2025 at 11:37:36AM +0100, Andrew Cooper wrote:

On 02/10/2025 11:22 am, Roger Pau Monne wrote:

Reading from the E9 port if the emergency console is active should return
0xe9 according to the documentation from Bochs:

https://bochs.sourceforge.io/doc/docbook/user/bochsrc.html

See `port_e9_hack` section description.

Fix Xen so it also returns the port address.  OSes can use it to detect
whether the emergency console is available or not.

Fixes: d1bd157fbc9b ("Big merge the HVM full-virtualisation abstractions.")
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>

Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>

That's been wrong for rather a long time.  How did you find it?

I came across the documentation above and I didn't remember Xen
returning any value for reads, which sadly was indeed true.

This was because I had the intention to suggest Alejandro to (also?) use
the port 0xe9 hack for printing from XTF, which should work for both
Xen and QEMU.


CC-ing Oleksii as you've tagged this for 4.21.

I was told that bugfixes didn't need a release-ack until hard code
freeze, which is the 31st of October?
I meant until the start of the hard code freeze, which is on October 4.
So there is no need for a release-ack for this patch.

Thanks.

~ Oleksii


  


--------------zyZ48vpMNzFA60oUHSnRUi4M--