From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by mx.groups.io with SMTP id smtpd.web09.7259.1619169067335035036 for ; Fri, 23 Apr 2021 02:11:07 -0700 Authentication-Results: mx.groups.io; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=M7tP4/Hv; spf=pass (domain: redhat.com, ip: 170.10.133.124, mailfrom: lersek@redhat.com) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1619169066; 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=PjVnrD3k1VF/Nrh1NbfVQNgt9NxFlcb2qMV6BHcCvRU=; b=M7tP4/Hvg4yOXZul0Jgvk3W724VL2XHx6f7WCxacLjfIfHUsPgpW52bbadQIpvkkG49oVA vcsMI49drBCjtuHbxrI4mvha41cd7Iicklxi7c+pkQ4D1TwxsHRZ1N36In5mpF/4lOqWxG +e0lOdug3FgACq2ka6j1/DXNJoXNCUw= 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-510-GqNMhMj4MWymNnZX3TjJyA-1; Fri, 23 Apr 2021 05:11:02 -0400 X-MC-Unique: GqNMhMj4MWymNnZX3TjJyA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 7F45E83DD20; Fri, 23 Apr 2021 09:11:00 +0000 (UTC) Received: from lacos-laptop-7.usersys.redhat.com (ovpn-115-2.ams2.redhat.com [10.36.115.2]) by smtp.corp.redhat.com (Postfix) with ESMTP id EB2D560C5F; Fri, 23 Apr 2021 09:10:57 +0000 (UTC) Subject: Re: [edk2-devel] [PATCH 2/3] OvmfPkg/VmgExitLib: Add support for new MMIO MOV opcodes To: Tom Lendacky , devel@edk2.groups.io Cc: Joerg Roedel , Borislav Petkov , Ard Biesheuvel , Jordan Justen , Brijesh Singh , James Bottomley , Jiewen Yao , Min Xu References: <79ed645c089ffab10716cdb8813f191f6e0afcfb.1618959281.git.thomas.lendacky@amd.com> <5d4e5bdd-65ea-7594-3b51-e33284fe990f@amd.com> From: "Laszlo Ersek" Message-ID: Date: Fri, 23 Apr 2021 11:10:56 +0200 MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 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 04/22/21 17:42, Tom Lendacky wrote: > On 4/22/21 9:15 AM, Tom Lendacky wrote: >> On 4/22/21 12:50 AM, Laszlo Ersek via groups.io wrote: >>> On 04/21/21 00:54, Lendacky, Thomas wrote: >>>> From: Tom Lendacky >>>> >>>> BZ: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugzilla.tianocore.org%2Fshow_bug.cgi%3Fid%3D3345&data=04%7C01%7Cthomas.lendacky%40amd.com%7C19a7d97e2a7b461830ed08d905528472%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637546674232278910%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=znSezOvpnItW7mHAJkr%2FtJtkQNFc2H0dG9STpmOpVqU%3D&reserved=0 >>>> >>>> Enabling TPM support results in guest termination of an SEV-ES guest >>>> because it uses MMIO opcodes that are not currently supported. >>>> >>>> Add support for the new MMIO opcodes (0xA0 - 0xA3), MOV instructions which >>>> use a memory offset directly encoded in the instruction. Also, add a DEBUG >>>> statement to identify an unsupported MMIO opcode being used. >>>> >>>> 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 | 99 +++++++++++++++++++ >>>> 1 file changed, 99 insertions(+) >>>> >>>> diff --git a/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c b/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c >>>> index 273f36499988..f9660b757d8e 100644 >>>> --- a/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c >>>> +++ b/OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c >>>> @@ -678,6 +678,7 @@ MmioExit ( >>>> UINTN Bytes; >>>> UINT64 *Register; >>>> UINT8 OpCode, SignByte; >>>> + UINTN Address; >>>> >>>> Bytes = 0; >>>> >>>> @@ -727,6 +728,51 @@ MmioExit ( >>>> } >>>> break; >>>> >>>> + // >>>> + // MMIO write (MOV moffsetX, aX) >>>> + // >>>> + case 0xA2: >>>> + Bytes = 1; >>>> + // >>>> + // fall through >>>> + // >>>> + case 0xA3: >>>> + Bytes = ((Bytes != 0) ? Bytes : >>>> + (InstructionData->DataSize == Size16Bits) ? 2 : >>>> + (InstructionData->DataSize == Size32Bits) ? 4 : >>>> + (InstructionData->DataSize == Size64Bits) ? 8 : >>>> + 0); >>>> + >>>> + InstructionData->ImmediateSize = (UINTN) (1 << InstructionData->AddrSize); >>>> + InstructionData->End += (UINTN) (1 << InstructionData->AddrSize); >>>> + >>>> + if (InstructionData->AddrSize == Size8Bits) { >>>> + Address = *(UINT8 *) InstructionData->Immediate; >>>> + } else if (InstructionData->AddrSize == Size16Bits) { >>>> + Address = *(UINT16 *) InstructionData->Immediate; >>>> + } else if (InstructionData->AddrSize == Size32Bits) { >>>> + Address = *(UINT32 *) InstructionData->Immediate; >>>> + } else { >>>> + Address = *(UINTN *) InstructionData->Immediate; >>>> + } >>> >>> (1) Can we simplify this as follows? >>> >>> InstructionData->ImmediateSize = 1 << InstructionData->AddrSize; >>> InstructionData->End += InstructionData->ImmediateSize; >>> Address = 0; >>> CopyMem (&Address, InstructionData->Immediate, >>> InstructionData->ImmediateSize); >> >> Yup, that can be done. > > "Address" is a type UINTN, but since this is X64 only code, an 8-byte copy > isn't an issue. Should I add a comment about that above the setting of > "Address"? Or should I convert "Address" to a UINT64 - although > ValidateMmioMemory expects a UINTN... Thoughts? Yes, I had the exact same thought process :) The comment looks good, but how about expressing it as a STATIC_ASSERT, with sizeof (UINTN) and sizeof (UINT64) being equal? (Alternatively, about MAX_UINT64 being equal to MAX_UINTN.) If you find that too verbose, a comment is good enough too, of course. Thanks! Laszlo > > Thanks, > Tom > >> >>> >>>> + >>>> + Status = ValidateMmioMemory (Ghcb, Address, Bytes); >>>> + if (Status != 0) { >>>> + return Status; >>>> + } >>>> + >>>> + ExitInfo1 = Address; >>>> + ExitInfo2 = Bytes; >>>> + CopyMem (Ghcb->SharedBuffer, &Regs->Rax, Bytes); >>>> + >>>> + Ghcb->SaveArea.SwScratch = (UINT64) Ghcb->SharedBuffer; >>>> + VmgSetOffsetValid (Ghcb, GhcbSwScratch); >>>> + Status = VmgExit (Ghcb, SVM_EXIT_MMIO_WRITE, ExitInfo1, ExitInfo2); >>>> + if (Status != 0) { >>>> + return Status; >>>> + } >>>> + break; >>>> + >>>> // >>>> // MMIO write (MOV reg/memX, immX) >>>> // >>>> @@ -809,6 +855,58 @@ MmioExit ( >>>> CopyMem (Register, Ghcb->SharedBuffer, Bytes); >>>> break; >>>> >>>> + // >>>> + // MMIO read (MOV aX, moffsetX) >>>> + // >>>> + case 0xA0: >>>> + Bytes = 1; >>>> + // >>>> + // fall through >>>> + // >>>> + case 0xA1: >>>> + Bytes = ((Bytes != 0) ? Bytes : >>>> + (InstructionData->DataSize == Size16Bits) ? 2 : >>>> + (InstructionData->DataSize == Size32Bits) ? 4 : >>>> + (InstructionData->DataSize == Size64Bits) ? 8 : >>>> + 0); >>>> + >>>> + InstructionData->ImmediateSize = (UINTN) (1 << InstructionData->AddrSize); >>>> + InstructionData->End += (UINTN) (1 << InstructionData->AddrSize); >>>> + >>>> + if (InstructionData->AddrSize == Size8Bits) { >>>> + Address = *(UINT8 *) InstructionData->Immediate; >>>> + } else if (InstructionData->AddrSize == Size16Bits) { >>>> + Address = *(UINT16 *) InstructionData->Immediate; >>>> + } else if (InstructionData->AddrSize == Size32Bits) { >>>> + Address = *(UINT32 *) InstructionData->Immediate; >>>> + } else { >>>> + Address = *(UINTN *) InstructionData->Immediate; >>>> + } >>> >>> (2) Similar question as (1). >> >> Will do. >> >>> >>>> + >>>> + Status = ValidateMmioMemory (Ghcb, Address, Bytes); >>>> + if (Status != 0) { >>>> + return Status; >>>> + } >>>> + >>>> + ExitInfo1 = Address; >>>> + ExitInfo2 = Bytes; >>>> + >>>> + Ghcb->SaveArea.SwScratch = (UINT64) Ghcb->SharedBuffer; >>>> + VmgSetOffsetValid (Ghcb, GhcbSwScratch); >>>> + Status = VmgExit (Ghcb, SVM_EXIT_MMIO_READ, ExitInfo1, ExitInfo2); >>>> + if (Status != 0) { >>>> + return Status; >>>> + } >>>> + >>>> + if (Bytes == 4) { >>>> + // >>>> + // Zero-extend for 32-bit operation >>>> + // >>>> + Regs->Rax = 0; >>>> + } >>> >>> (3) This is also seen with opcode 0x8B, but can you remind me please why >>> we ignore (Bytes == 1) and (Bytes == 2) for zero extension? >> >> That comes from the APM Vol 3, Table B-1, that says, in 64-bit mode, for a >> 32-bit operand size the 32-bit register results are zero-extended to 64-bits. >> >>> >>>> + CopyMem (&Regs->Rax, Ghcb->SharedBuffer, Bytes); >>>> + break; >>>> + >>>> // >>>> // MMIO read w/ zero-extension ((MOVZX regX, reg/memX) >>>> // >>>> @@ -886,6 +984,7 @@ MmioExit ( >>>> break; >>>> >>>> default: >>>> + DEBUG ((DEBUG_INFO, "Invalid MMIO opcode (%x)\n", OpCode)); >>>> Status = GP_EXCEPTION; >>>> ASSERT (FALSE); >>>> } >>>> >>> >>> (4) We should use the DEBUG_ERROR log mask here. >> >> Will change. >> >> Thanks, >> Tom >> >>> >>> Thanks >>> Laszlo >>> >>> >>> >>> >>> >>> >