From: Joerg Roedel <joro@8bytes.org> To: x86@kernel.org, Hyunwook Baek <baekhw@google.com> Cc: Joerg Roedel <joro@8bytes.org>, Joerg Roedel <jroedel@suse.de>, stable@vger.kernel.org, hpa@zytor.com, Andy Lutomirski <luto@kernel.org>, Dave Hansen <dave.hansen@linux.intel.com>, Peter Zijlstra <peterz@infradead.org>, Jiri Slaby <jslaby@suse.cz>, Dan Williams <dan.j.williams@intel.com>, Tom Lendacky <thomas.lendacky@amd.com>, Juergen Gross <jgross@suse.com>, Kees Cook <keescook@chromium.org>, David Rientjes <rientjes@google.com>, Cfir Cohen <cfir@google.com>, Erdem Aktas <erdemaktas@google.com>, Masami Hiramatsu <mhiramat@kernel.org>, Mike Stunes <mstunes@vmware.com>, Sean Christopherson <seanjc@google.com>, Martin Radev <martin.b.radev@gmail.com>, Arvind Sankar <nivedita@alum.mit.edu>, 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 [thread overview] Message-ID: <20210512075445.18935-5-joro@8bytes.org> (raw) In-Reply-To: <20210512075445.18935-1-joro@8bytes.org> From: Joerg Roedel <jroedel@suse.de> 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 <jroedel@suse.de> --- 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
WARNING: multiple messages have this Message-ID (diff)
From: Joerg Roedel <joro@8bytes.org> To: x86@kernel.org, Hyunwook Baek <baekhw@google.com> Cc: kvm@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>, Dave Hansen <dave.hansen@linux.intel.com>, virtualization@lists.linux-foundation.org, Arvind Sankar <nivedita@alum.mit.edu>, hpa@zytor.com, Jiri Slaby <jslaby@suse.cz>, Joerg Roedel <joro@8bytes.org>, David Rientjes <rientjes@google.com>, Martin Radev <martin.b.radev@gmail.com>, Tom Lendacky <thomas.lendacky@amd.com>, Joerg Roedel <jroedel@suse.de>, Kees Cook <keescook@chromium.org>, Cfir Cohen <cfir@google.com>, linux-coco@lists.linux.dev, Andy Lutomirski <luto@kernel.org>, Dan Williams <dan.j.williams@intel.com>, Juergen Gross <jgross@suse.com>, Mike Stunes <mstunes@vmware.com>, Sean Christopherson <seanjc@google.com>, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Masami Hiramatsu <mhiramat@kernel.org>, Erdem Aktas <erdemaktas@google.com> 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 [thread overview] Message-ID: <20210512075445.18935-5-joro@8bytes.org> (raw) In-Reply-To: <20210512075445.18935-1-joro@8bytes.org> From: Joerg Roedel <jroedel@suse.de> 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 <jroedel@suse.de> --- 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 _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
next prev parent reply other threads:[~2021-05-12 7:55 UTC|newest] Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-05-12 7:54 [PATCH 0/6] x86/sev-es: Fixes for SEV-ES guest support Joerg Roedel 2021-05-12 7:54 ` Joerg Roedel 2021-05-12 7:54 ` [PATCH 1/6] x86/sev-es: Don't return NULL from sev_es_get_ghcb() Joerg Roedel 2021-05-12 7:54 ` Joerg Roedel 2021-05-12 7:54 ` [PATCH 2/6] x86/sev-es: Forward page-faults which happen during emulation Joerg Roedel 2021-05-12 7:54 ` Joerg Roedel 2021-05-12 17:31 ` Sean Christopherson 2021-05-19 13:16 ` Joerg Roedel 2021-05-19 13:16 ` Joerg Roedel 2021-05-12 7:54 ` [PATCH 3/6] x86/sev-es: Use __put_user()/__get_user Joerg Roedel 2021-05-12 7:54 ` Joerg Roedel 2021-05-12 8:04 ` David Laight 2021-05-12 8:04 ` David Laight 2021-05-12 8:04 ` David Laight 2021-05-12 8:16 ` Juergen Gross 2021-05-12 8:16 ` Juergen Gross via Virtualization 2021-05-12 8:16 ` Juergen Gross 2021-05-12 8:50 ` 'Joerg Roedel' 2021-05-12 8:50 ` 'Joerg Roedel' 2021-05-12 8:50 ` 'Joerg Roedel' 2021-05-12 8:58 ` Juergen Gross 2021-05-12 8:58 ` Juergen Gross via Virtualization 2021-05-12 8:58 ` Juergen Gross 2021-05-12 9:31 ` David Laight 2021-05-12 9:31 ` David Laight 2021-05-12 9:31 ` David Laight 2021-05-12 9:32 ` Joerg Roedel 2021-05-12 9:32 ` Joerg Roedel 2021-05-12 9:32 ` Joerg Roedel 2021-05-19 11:33 ` 'Joerg Roedel' 2021-05-19 11:33 ` 'Joerg Roedel' 2021-05-19 11:33 ` 'Joerg Roedel' 2021-05-12 8:37 ` 'Joerg Roedel' 2021-05-12 8:37 ` 'Joerg Roedel' 2021-05-12 8:37 ` 'Joerg Roedel' 2021-05-12 15:59 ` Dave Hansen 2021-05-12 15:59 ` Dave Hansen 2021-05-12 15:59 ` Dave Hansen 2021-05-12 15:57 ` Dave Hansen 2021-05-12 15:57 ` Dave Hansen 2021-05-12 16:00 ` Joerg Roedel 2021-05-12 16:00 ` Joerg Roedel 2021-05-12 7:54 ` Joerg Roedel [this message] 2021-05-12 7:54 ` [PATCH 4/6] Revert "x86/sev-es: Handle string port IO to kernel memory properly" Joerg Roedel 2021-05-12 17:38 ` Sean Christopherson 2021-05-19 12:22 ` Joerg Roedel 2021-05-19 12:22 ` Joerg Roedel 2021-05-12 7:54 ` [PATCH 5/6] x86/sev-es: Fix error message in runtime #VC handler Joerg Roedel 2021-05-12 7:54 ` Joerg Roedel 2021-05-12 7:54 ` [PATCH 6/6] x86/sev-es: Leave NMI-mode before sending signals Joerg Roedel 2021-05-12 7:54 ` Joerg Roedel
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