From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) by mx.groups.io with SMTP id smtpd.web09.8219.1619069314918157571 for ; Wed, 21 Apr 2021 22:28:35 -0700 Authentication-Results: mx.groups.io; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=BXiy9wA5; spf=pass (domain: redhat.com, ip: 216.205.24.124, mailfrom: lersek@redhat.com) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1619069314; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=+GvCUH/s1irHqRU0h9HgHk4v6x4yvTvYLOODdPyDjcc=; b=BXiy9wA5kfooFWMMSSkYUJYGFzfacqPvjy/6LHtmF+eJUuEnXZ/GgxnSxqaRpiEG7esJHc gGP84S2rLHgLctLhApxvRNLwTiSgNZkMDCj5hUa8UOVE0O4tS7S58cFEgzu2R86Nyduaf5 4VuobGjCBAKUHBCWanhL3icdV21tQaU= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-463-_WYbbrsyN4WZJXT5Lgqs2g-1; Thu, 22 Apr 2021 01:28:30 -0400 X-MC-Unique: _WYbbrsyN4WZJXT5Lgqs2g-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8B8938189D3; Thu, 22 Apr 2021 05:28:28 +0000 (UTC) Received: from lacos-laptop-7.usersys.redhat.com (ovpn-112-151.ams2.redhat.com [10.36.112.151]) by smtp.corp.redhat.com (Postfix) with ESMTP id 47DD619726; Thu, 22 Apr 2021 05:28:25 +0000 (UTC) Subject: Re: [edk2-devel] [PATCH 1/3] OvfmPkg/VmgExitLib: Properly decode MMIO MOVZX and MOVSX opcodes To: devel@edk2.groups.io, thomas.lendacky@amd.com Cc: Joerg Roedel , Borislav Petkov , Ard Biesheuvel , Jordan Justen , Brijesh Singh , James Bottomley , Jiewen Yao , Min Xu References: <71864a75c680c4f7f07ebf9611c9cc2d351ce5d0.1618959281.git.thomas.lendacky@amd.com> From: "Laszlo Ersek" Message-ID: <7bf6b4ce-85c7-578e-973a-f976bdfa706b@redhat.com> Date: Thu, 22 Apr 2021 07:28:25 +0200 MIME-Version: 1.0 In-Reply-To: <71864a75c680c4f7f07ebf9611c9cc2d351ce5d0.1618959281.git.thomas.lendacky@amd.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=lersek@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit On 04/21/21 00:54, Lendacky, Thomas wrote: > From: Tom Lendacky > > BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3345 > > The MOVZX and MOVSX instructions use the ModRM byte in the instruction, > but the instruction decoding support was not decoding it. This resulted > in invalid decoding and failing of the MMIO operation. Also, when > performing the zero-extend or sign-extend operation, the memory operation > should be using the size, and not the size enumeration value. > > Add the ModRM byte decoding for the MOVZX and MOVSX opcodes and use the > true data size to perform the extend operations. Additionally, add a > DEBUG statement identifying the MMIO address being flagged as encrypted > during the MMIO address validation. > > Fixes: c45f678a1ea2080344e125dc55b14e4b9f98483d > Cc: Laszlo Ersek > Cc: Ard Biesheuvel > Cc: Jordan Justen > Cc: Brijesh Singh > Cc: James Bottomley > Cc: Jiewen Yao > Cc: Min Xu > Signed-off-by: Tom Lendacky > --- > OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c b/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c > index 24259060fd65..273f36499988 100644 > --- a/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c > +++ b/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c > @@ -643,6 +643,7 @@ ValidateMmioMemory ( > // > // Any state other than unencrypted is an error, issue a #GP. > // > + DEBUG ((DEBUG_INFO, "MMIO using encrypted memory: %lx\n", MemoryAddress)); > GpEvent.Uint64 = 0; > GpEvent.Elements.Vector = GP_EXCEPTION; > GpEvent.Elements.Type = GHCB_EVENT_INJECTION_TYPE_EXCEPTION; (1) This can potentially generate a large number of debug messages; please use the DEBUG_VERBOSE log mask. (2) "MemoryAddress" has type UINTN, but %lx takes UINT64. Given that this is X64-only code, functionally there is no bug, but it's still cleaner to pass "(UINT64)MemoryAddress" to %lx. With that: Acked-by: Laszlo Ersek Thanks Laszlo > @@ -817,6 +818,7 @@ MmioExit ( > // fall through > // > case 0xB7: > + DecodeModRm (Regs, InstructionData); > Bytes = (Bytes != 0) ? Bytes : 2; > > Status = ValidateMmioMemory (Ghcb, InstructionData->Ext.RmData, Bytes); > @@ -835,7 +837,7 @@ MmioExit ( > } > > Register = GetRegisterPointer (Regs, InstructionData->Ext.ModRm.Reg); > - SetMem (Register, InstructionData->DataSize, 0); > + SetMem (Register, (UINTN) (1 << InstructionData->DataSize), 0); > CopyMem (Register, Ghcb->SharedBuffer, Bytes); > break; > > @@ -848,6 +850,7 @@ MmioExit ( > // fall through > // > case 0xBF: > + DecodeModRm (Regs, InstructionData); > Bytes = (Bytes != 0) ? Bytes : 2; > > Status = ValidateMmioMemory (Ghcb, InstructionData->Ext.RmData, Bytes); > @@ -878,7 +881,7 @@ MmioExit ( > } > > Register = GetRegisterPointer (Regs, InstructionData->Ext.ModRm.Reg); > - SetMem (Register, InstructionData->DataSize, SignByte); > + SetMem (Register, (UINTN) (1 << InstructionData->DataSize), SignByte); > CopyMem (Register, Ghcb->SharedBuffer, Bytes); > break; > >