From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from fanzine2.igalia.com (fanzine2.igalia.com [213.97.179.56]) (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 B00253630AC for ; Sat, 22 Aug 2026 18:33:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.97.179.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787423604; cv=none; b=g5Y0zDHOiaTacH+HIngUhlyYfTxyXE8/T11jLaqrYEJDH12EVYqtQPVZQmHZel2ev5dQC/rnu3S1VVzb2M8bNWaZue4YDKMD9h8iLCMta/Rj9I41bzL3IWLmFoyHI0HQXg+yo9WRjRKhoNXiqxWoe0XxMLltHChAvnobEn1YxX0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787423604; c=relaxed/simple; bh=OkIa3z1AcMrSUna4J8u5Lsiefie52xz4ktG4ssBuhdA=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=Ka2Bg2pv77vSQlm6KFZNCDy/pMg5JiAgOGktAeSqRg8fEPiIIsY0Z4uvXZ5tdWNz0UOynUCHaQF1YrxbrB03PIPAIreLpkYS9zeuPn6BBcW7/0+MzluSfWAlOFht4D/9MHyq06K17+PUlXsHGLZ2DqKJiie57fCHoXUFbHSdMBk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=igalia.com; spf=pass smtp.mailfrom=igalia.com; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b=H7scH/f9; arc=none smtp.client-ip=213.97.179.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=igalia.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=igalia.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=igalia.com header.i=@igalia.com header.b="H7scH/f9" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Cc:To:Message-Id:Content-Transfer-Encoding:Content-Type: MIME-Version:Subject:Date:From:From:Reply-To; bh=H2GAc7mtrFpKl87p+adcJZhrkVbc1evwDywNzt1ulrU=; b=H7scH/f9ODImbbUeyRMgVs7MXe Nr3swyCLfgndRrDO16yiFdMGz4KKClK2UPeUFBZKVfLxmIqMoKb3T/QUykYiNYSaZ+lSiBkOAWs8K mPeTyiyzWVBYg9kn5vwI13IGSEJN/hnVR7zvusHc8vC26fNDy9EUiMtHFDEj94edspLbLPj0qPZq4 ef0YCA0Glz2UqWlN13YuFbgT6H+EpD/oSjikDrT4RmtRcavY+AxKlreaSo2i+Izsrzy5b2QqYq13E x23H4ImJH+EvyLOnra8OZnARhQqFHaeyv6Doe0SPuSjiGkp9KCVP5E1viUqPqeS0iUv4cIYeaQW6V m0Hwf4Qg==; Received: from 186-249-148-4.shared.desktop.com.br ([186.249.148.4] helo=[127.0.1.1]) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1wxqWj-007bWT-Vu; Sat, 22 Aug 2026 20:33:10 +0200 From: Mauricio Faria de Oliveira Date: Sat, 22 Aug 2026 15:33:20 -0300 Subject: [PATCH v9 4/5] x86/cpuid: fix unbootable VMs by really inlining memcmp() in hypervisor_cpuid_base() Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260822-pvh-kasan-inline-v9-4-e70ef3b75b6a@igalia.com> References: <20260822-pvh-kasan-inline-v9-0-e70ef3b75b6a@igalia.com> In-Reply-To: <20260822-pvh-kasan-inline-v9-0-e70ef3b75b6a@igalia.com> To: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Juergen Gross , Alexey Dobriyan , Boris Ostrovsky , Jan Beulich , Brian Gerst Cc: kernel-dev@igalia.com, linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org, Mauricio Faria de Oliveira X-Mailer: b4 0.14.2 Even with __builtin the compiler may decide to use the out of line function instead of the inline implementation. The existing code is broken with gcc-14/15 but not gcc-12/13 (Ubuntu 25.10) and vmlinux no longer boots with CONFIG_PVH if CONFIG_KASAN_GENERIC is set. For testing purposes, if the size argument is reduced from 12 to 8 then the compiler decides to use the inline implementation; that shows results vary. Switch the builtin to the inline implementation to address it. Fixes: 416a33c9afce ("x86/cpu: fix unbootable VMs by inlining memcmp() in hypervisor_cpuid_base()") Signed-off-by: Mauricio Faria de Oliveira Reviewed-by: Juergen Gross --- arch/x86/include/asm/cpuid/api.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/include/asm/cpuid/api.h b/arch/x86/include/asm/cpuid/api.h index 82eddfa2347b32b76c2ea9b85f005ca5416ac71f..2d9f3d4d63de6e721f275d9e80d372edbdfedf30 100644 --- a/arch/x86/include/asm/cpuid/api.h +++ b/arch/x86/include/asm/cpuid/api.h @@ -204,7 +204,7 @@ static inline u32 cpuid_base_hypervisor(const char *sig, u32 leaves) * from PVH early boot code before instrumentation is set up * and memcmp() itself may be instrumented. */ - if (!__builtin_memcmp(sig, signature, 12) && + if (!__inline_memcmp(sig, signature, 12) && (leaves == 0 || ((eax - base) >= leaves))) return base; } -- 2.47.3