From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from theia.8bytes.org (8bytes.org [81.169.241.247]) (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 7F2F82FB0 for ; Wed, 12 May 2021 07:55:17 +0000 (UTC) Received: from cap.home.8bytes.org (p549ad305.dip0.t-ipconnect.de [84.154.211.5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (No client certificate requested) by theia.8bytes.org (Postfix) with ESMTPSA id A32B141D; Wed, 12 May 2021 09:55:09 +0200 (CEST) From: Joerg Roedel To: x86@kernel.org, Hyunwook Baek Cc: Joerg Roedel , Joerg Roedel , stable@vger.kernel.org, hpa@zytor.com, Andy Lutomirski , Dave Hansen , Peter Zijlstra , Jiri Slaby , Dan Williams , Tom Lendacky , Juergen Gross , Kees Cook , David Rientjes , Cfir Cohen , Erdem Aktas , Masami Hiramatsu , Mike Stunes , Sean Christopherson , Martin Radev , Arvind Sankar , linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org Subject: [PATCH 4/6] Revert "x86/sev-es: Handle string port IO to kernel memory properly" Date: Wed, 12 May 2021 09:54:43 +0200 Message-Id: <20210512075445.18935-5-joro@8bytes.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210512075445.18935-1-joro@8bytes.org> References: <20210512075445.18935-1-joro@8bytes.org> X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Joerg Roedel This reverts commit 7024f60d655272bd2ca1d3a4c9e0a63319b1eea1. The commit reverted here introduces a short-cut into the #VC handlers memory access code which only works reliably in task context. But the kernels #VC handler can be invoked from any context, making the access_ok() call trigger a warning with CONFIG_DEBUG_ATOMIC_SLEEP enabled. Also the memcpy() used in the reverted patch is wrong, as it has no page-fault handling. Access to kernel memory can also fault due to kernel bugs, and those should not be reported as faults from the #VC handler but as bugs of their real call-site, which is correctly later done from vc_forward_exception(). Fixes: 7024f60d6552 ("x86/sev-es: Handle string port IO to kernel memory properly") Cc: stable@vger.kernel.org # v5.11 Signed-off-by: Joerg Roedel --- arch/x86/kernel/sev.c | 12 ------------ 1 file changed, 12 deletions(-) diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index 110b39345b40..f4f319004713 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -333,12 +333,6 @@ static enum es_result vc_write_mem(struct es_em_ctxt *ctxt, u16 d2; u8 d1; - /* If instruction ran in kernel mode and the I/O buffer is in kernel space */ - if (!user_mode(ctxt->regs) && !access_ok(target, size)) { - memcpy(dst, buf, size); - return ES_OK; - } - switch (size) { case 1: memcpy(&d1, buf, 1); @@ -388,12 +382,6 @@ static enum es_result vc_read_mem(struct es_em_ctxt *ctxt, u16 d2; u8 d1; - /* If instruction ran in kernel mode and the I/O buffer is in kernel space */ - if (!user_mode(ctxt->regs) && !access_ok(s, size)) { - memcpy(buf, src, size); - return ES_OK; - } - switch (size) { case 1: if (__get_user(d1, s)) -- 2.31.1