From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 0B752176238; Thu, 28 May 2026 15:32:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779982338; cv=none; b=ktzgLVHHb34cWgtKCkA32t7jfHQ1dcF+0vsyOgFLM4KiKZkmuX0UxOO5vEbdQp7FSfBfS0xescz6n62DqV53qDDOLIpROYV5I9mkcTUgC/O8Th7dPMMP3TRzRl48Jwe6SxA5V0p+oG3CQAV8JWDGDF/7/+OOuX5xGNfrCICypLo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779982338; c=relaxed/simple; bh=20nB2Unf4TEU/nmf0brbMpnEcKQdoJB5ubCBy0YTZ5A=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=OHCp/zBCaTlNJZYu5I1gC0aV/jbbUO8+hmHVREQB2aM4IV6QcfNH4oG527EFe7tH2k/cK3a1saMdRt9KkmwC7M7ru+UyQUxCmjPk7TwMnbQJov/PL3FCg1D5V9XCbsx9kE39QzoiZpEzgMKeXX8PU8xYn+iKG+3dh21eNjxKt/o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=casper.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=VPrTIA1u; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=casper.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="VPrTIA1u" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=MIME-Version:Content-Type:References: In-Reply-To:Date:Cc:To:From:Subject:Message-ID:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=20nB2Unf4TEU/nmf0brbMpnEcKQdoJB5ubCBy0YTZ5A=; b=VPrTIA1uFgnWq8LmI37urVtc9/ qufgRLKZ2u44C6YMeXWhBmSNq9CudN7BDEIElX8DAJzufAprB4ZhQRT44KJBZHpAb5C0Wv+G6ZO+W glKKvOI3CCilZtW59CNUStq3RBX41o1khUtZ7ysBqlvN1SbNFbRDbYyDnbskuyV3l/zlZBEC4l/vC zDTT3g9trzwJcok/z+JUvEYaJTlRVVk8DZcBFH98pyiy7xADEyw/BD//ZcgJpGC/oE9W5sdLHtQ2q e1D7M1E9Yakg0gxea1bsjf61wnTenZYJve8Sb3Zl29uDE8TCgXBETBe67wSosibOfckJqaA9rH7gf xdkNb+LA==; Received: from 54-240-197-239.amazon.com ([54.240.197.239] helo=edge-cache-150.e-ind6.amazon.com) by casper.infradead.org with esmtpsa (Exim 4.99.1 #2 (Red Hat Linux)) id 1wSciL-00000004R24-0V3n; Thu, 28 May 2026 15:32:07 +0000 Message-ID: Subject: Re: [PATCH v2 0/6] KVM/x86: Drop "1" as MSR emulation return value From: David Woodhouse To: =?ISO-8859-1?Q?J=FCrgen_Gro=DF?= , Sean Christopherson Cc: linux-kernel@vger.kernel.org, x86@kernel.org, kvm@vger.kernel.org, linux-coco@lists.linux.dev, Paolo Bonzini , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Vitaly Kuznetsov , Kiryl Shutsemau , Rick Edgecombe , Paul Durrant Date: Thu, 28 May 2026 16:32:04 +0100 In-Reply-To: <8d3f3cbe-89ca-44df-b35f-90c2724e9154@suse.com> References: <20260528113605.267111-1-jgross@suse.com> <476964db-837a-45d8-a647-c5a2ea8b0cb6@suse.com> <8d3f3cbe-89ca-44df-b35f-90c2724e9154@suse.com> Content-Type: multipart/signed; micalg="sha-256"; protocol="application/pkcs7-signature"; boundary="=-GJG805fU/68s8LS6pg3j" User-Agent: Evolution 3.52.3-0ubuntu1.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html --=-GJG805fU/68s8LS6pg3j Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Thu, 2026-05-28 at 16:33 +0200, J=C3=BCrgen Gro=C3=9F wrote: > On 28.05.26 15:21, Sean Christopherson wrote: > > On Thu, May 28, 2026, J=C3=BCrgen Gro=C3=9F wrote: > > > On 28.05.26 15:09, Sean Christopherson wrote: > > > > On Thu, May 28, 2026, Juergen Gross wrote: > > > > > Please disregard this series, there is one complication sashiko m= ade me > > > > > aware of. > > > >=20 > > > > Sashiko beat me to the punch. :-) > > > >=20 > > > > See commit 2368048bf5c2 ("KVM: x86: Signal #GP, not -EPERM, on bad = WRMSR(MCi_CTL/STATUS)") > > > > for a real world example of how things can and will go wrong. > > >=20 > > > Yeah, with Sashiko's pointer it was easy to spot. > > >=20 > > > Question now is whether the already existing cases of -errno passed a= s return > > > value are wrong or on purpose. > >=20 > > What are the existing cases? >=20 > Found another one: >=20 > kvm_xen_write_hypercall_page() (called by kvm_set_msr_common()) You mean in the case where it's using the user-provided hypercall page, and can't copy from the buffer that the VMM provided? I think that's correct to return -errno via PTR_ERR() and let the guest die? 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