From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 41C9382139 for ; Fri, 17 Feb 2017 12:52:02 -0800 (PST) Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9FD4BD59AD; Fri, 17 Feb 2017 20:52:02 +0000 (UTC) Received: from lacos-laptop-7.usersys.redhat.com (ovpn-116-41.phx2.redhat.com [10.3.116.41]) by int-mx13.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id v1HKq0VZ010623; Fri, 17 Feb 2017 15:52:01 -0500 To: Jordan Justen , edk2-devel-01 References: <20170216204137.30221-1-lersek@redhat.com> <20170216204137.30221-5-lersek@redhat.com> <148736008994.16092.5271721175250835615@jljusten-ivb> From: Laszlo Ersek Message-ID: <0725da37-9af6-1dbd-215d-59819ee8e88a@redhat.com> Date: Fri, 17 Feb 2017 21:51:59 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.1 MIME-Version: 1.0 In-Reply-To: <148736008994.16092.5271721175250835615@jljusten-ivb> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.26 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Fri, 17 Feb 2017 20:52:02 +0000 (UTC) Subject: Re: [PATCH 4/5] OvmfPkg/AcpiPlatformDxe: implement the QEMU_LOADER_WRITE_POINTER command X-BeenThere: edk2-devel@lists.01.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: EDK II Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 17 Feb 2017 20:52:02 -0000 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit On 02/17/17 20:34, Jordan Justen wrote: > On 2017-02-16 12:41:36, Laszlo Ersek wrote: >> The QEMU_LOADER_WRITE_POINTER command instructs the firmware to write the >> address of a field within a previously allocated/downloaded fw_cfg blob >> into another (writeable) fw_cfg file at a specific offset. >> >> Put differently, QEMU_LOADER_WRITE_POINTER propagates, to QEMU, the >> address that QEMU_LOADER_ALLOCATE placed the designated fw_cfg blob at, as >> adjusted for the given field inside the allocated blob. >> >> The implementation is similar to that of QEMU_LOADER_ADD_POINTER. Since >> here we "patch" a pointer object in "fw_cfg file space", not guest memory >> space, we utilize the QemuFwCfgSkipBytes() and QemuFwCfgWriteBytes() APIs >> completed in commit range 465663e9f128..7fcb73541299. >> >> An interesting aspect is that QEMU_LOADER_WRITE_POINTER creates a >> host-level reference to a guest memory location. Therefore, if we fail to >> process the linker/loader script for any reason, we have to clear out >> those references first, before we release the guest memory allocations in >> response to the error. >> >> Cc: Jordan Justen >> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=359 >> Contributed-under: TianoCore Contribution Agreement 1.0 >> Signed-off-by: Laszlo Ersek >> --- >> OvmfPkg/AcpiPlatformDxe/QemuFwCfgAcpi.c | 171 +++++++++++++++++++- >> 1 file changed, 168 insertions(+), 3 deletions(-) >> >> diff --git a/OvmfPkg/AcpiPlatformDxe/QemuFwCfgAcpi.c b/OvmfPkg/AcpiPlatformDxe/QemuFwCfgAcpi.c >> index 404589cad0b7..de827c2df204 100644 >> --- a/OvmfPkg/AcpiPlatformDxe/QemuFwCfgAcpi.c >> +++ b/OvmfPkg/AcpiPlatformDxe/QemuFwCfgAcpi.c >> @@ -350,10 +350,147 @@ ProcessCmdAddChecksum ( >> AddChecksum->ResultOffset, AddChecksum->Start, AddChecksum->Length)); >> return EFI_SUCCESS; >> } >> >> >> +/** >> + Process a QEMU_LOADER_WRITE_POINTER command. >> + >> + @param[in] WritePointer The QEMU_LOADER_WRITE_POINTER command to process. >> + >> + @param[in] Tracker The ORDERED_COLLECTION tracking the BLOB user >> + structures created thus far. >> + >> + @retval EFI_PROTOCOL_ERROR Malformed fw_cfg file name(s) have been found in >> + WritePointer. Or, the WritePointer command >> + references a file unknown to Tracker or the >> + fw_cfg directory. Or, the pointer object to >> + rewrite has invalid location, size, or initial >> + relative value. Or, the pointer value to store >> + does not fit in the given pointer size. >> + >> + @retval EFI_SUCCESS The pointer object inside the writeable fw_cfg >> + file has been written. >> +**/ >> +STATIC >> +EFI_STATUS >> +ProcessCmdWritePointer ( >> + IN CONST QEMU_LOADER_WRITE_POINTER *WritePointer, >> + IN CONST ORDERED_COLLECTION *Tracker >> + ) >> +{ >> + RETURN_STATUS Status; >> + FIRMWARE_CONFIG_ITEM PointerItem; >> + UINTN PointerItemSize; >> + ORDERED_COLLECTION_ENTRY *PointeeEntry; >> + BLOB *PointeeBlob; >> + UINT64 PointerValue; >> + >> + if (WritePointer->PointerFile[QEMU_LOADER_FNAME_SIZE - 1] != '\0' || >> + WritePointer->PointeeFile[QEMU_LOADER_FNAME_SIZE - 1] != '\0') { >> + DEBUG ((DEBUG_ERROR, "%a: malformed file name\n", __FUNCTION__)); >> + return EFI_PROTOCOL_ERROR; >> + } >> + >> + Status = QemuFwCfgFindFile ((CONST CHAR8 *)WritePointer->PointerFile, >> + &PointerItem, &PointerItemSize); >> + PointeeEntry = OrderedCollectionFind (Tracker, WritePointer->PointeeFile); >> + if (RETURN_ERROR (Status) || PointeeEntry == NULL) { >> + DEBUG ((DEBUG_ERROR, >> + "%a: invalid fw_cfg file or blob reference \"%a\" / \"%a\"\n", >> + __FUNCTION__, WritePointer->PointerFile, WritePointer->PointeeFile)); >> + return EFI_PROTOCOL_ERROR; >> + } >> + >> + if ((WritePointer->PointerSize != 1 && WritePointer->PointerSize != 2 && >> + WritePointer->PointerSize != 4 && WritePointer->PointerSize != 8) || >> + (PointerItemSize < WritePointer->PointerSize) || >> + (PointerItemSize - WritePointer->PointerSize < >> + WritePointer->PointerOffset)) { >> + DEBUG ((DEBUG_ERROR, "%a: invalid pointer location or size in \"%a\"\n", >> + __FUNCTION__, WritePointer->PointerFile)); >> + return EFI_PROTOCOL_ERROR; >> + } >> + >> + PointeeBlob = OrderedCollectionUserStruct (PointeeEntry); >> + PointerValue = WritePointer->PointeeOffset; >> + if (PointerValue >= PointeeBlob->Size) { >> + DEBUG ((DEBUG_ERROR, "%a: invalid PointeeOffset\n", __FUNCTION__)); >> + return EFI_PROTOCOL_ERROR; >> + } >> + >> + // >> + // The memory allocation system ensures that the address of the byte past the >> + // last byte of any allocated object is expressible (no wraparound). >> + // >> + ASSERT ((UINTN)PointeeBlob->Base <= MAX_ADDRESS - PointeeBlob->Size); >> + >> + PointerValue += (UINT64)(UINTN)PointeeBlob->Base; >> + if (RShiftU64 ( >> + RShiftU64 (PointerValue, WritePointer->PointerSize * 8 - 1), 1) != 0) { > > What do you think of this instead? > > if (WritePointer->PointerSize < 8 && > RShiftU64 (PointerValue, WritePointer->PointerSize * 8) != 0) { Entirely valid, but then I should update ProcessCmdAddPointer() similarly :) Also, I'll feel less smart about myself! ;) If that's OK with you, I'll fix it up later. (I'll collect these warts into another BZ, as long as they aren't critical.) BTW, today I had a successful end-to-end (VM migration) test with Ben's QEMU v8 series, and this one for OVMF; that is, VMGENID worked "in action" with a Windows Server 2012 R2 guest. In the guest, I used a small Windows application from a colleague to wait for the VMGENID to change (and to report / query it). > > Patches 1-4 Reviewed-by: Jordan Justen Thank you very much! Laszlo > >> + DEBUG ((DEBUG_ERROR, "%a: pointer value unrepresentable in \"%a\"\n", >> + __FUNCTION__, WritePointer->PointerFile)); >> + return EFI_PROTOCOL_ERROR; >> + } >> + >> + QemuFwCfgSelectItem (PointerItem); >> + QemuFwCfgSkipBytes (WritePointer->PointerOffset); >> + QemuFwCfgWriteBytes (WritePointer->PointerSize, &PointerValue); >> + >> + // >> + // Because QEMU has now learned PointeeBlob->Base, we must mark PointeeBlob >> + // as unreleasable, for the case when the whole linker/loader script is >> + // handled successfully. >> + // >> + PointeeBlob->HostsOnlyTableData = FALSE; >> + >> + DEBUG ((DEBUG_VERBOSE, "%a: PointerFile=\"%a\" PointeeFile=\"%a\" " >> + "PointerOffset=0x%x PointeeOffset=0x%x PointerSize=%d\n", __FUNCTION__, >> + WritePointer->PointerFile, WritePointer->PointeeFile, >> + WritePointer->PointerOffset, WritePointer->PointeeOffset, >> + WritePointer->PointerSize)); >> + return EFI_SUCCESS; >> +} >> + >> + >> +/** >> + Undo a QEMU_LOADER_WRITE_POINTER command. >> + >> + This function revokes (zeroes out) a guest memory reference communicated to >> + QEMU earlier. The caller is responsible for invoking this function only on >> + such QEMU_LOADER_WRITE_POINTER commands that have been successfully processed >> + by ProcessCmdWritePointer(). >> + >> + @param[in] WritePointer The QEMU_LOADER_WRITE_POINTER command to undo. >> +**/ >> +STATIC >> +VOID >> +UndoCmdWritePointer ( >> + IN CONST QEMU_LOADER_WRITE_POINTER *WritePointer >> + ) >> +{ >> + RETURN_STATUS Status; >> + FIRMWARE_CONFIG_ITEM PointerItem; >> + UINTN PointerItemSize; >> + UINT64 PointerValue; >> + >> + Status = QemuFwCfgFindFile ((CONST CHAR8 *)WritePointer->PointerFile, >> + &PointerItem, &PointerItemSize); >> + ASSERT_RETURN_ERROR (Status); >> + >> + PointerValue = 0; >> + QemuFwCfgSelectItem (PointerItem); >> + QemuFwCfgSkipBytes (WritePointer->PointerOffset); >> + QemuFwCfgWriteBytes (WritePointer->PointerSize, &PointerValue); >> + >> + DEBUG ((DEBUG_VERBOSE, >> + "%a: PointerFile=\"%a\" PointerOffset=0x%x PointerSize=%d\n", __FUNCTION__, >> + WritePointer->PointerFile, WritePointer->PointerOffset, >> + WritePointer->PointerSize)); >> +} >> + >> + >> // >> // We'll be saving the keys of installed tables so that we can roll them back >> // in case of failure. 128 tables should be enough for anyone (TM). >> // >> #define INSTALLED_TABLES_MAX 128 >> @@ -559,10 +696,11 @@ InstallQemuFwCfgTables ( >> EFI_STATUS Status; >> FIRMWARE_CONFIG_ITEM FwCfgItem; >> UINTN FwCfgSize; >> QEMU_LOADER_ENTRY *LoaderStart; >> CONST QEMU_LOADER_ENTRY *LoaderEntry, *LoaderEnd; >> + CONST QEMU_LOADER_ENTRY *WritePointerSubsetEnd; >> ORIGINAL_ATTRIBUTES *OriginalPciAttributes; >> UINTN OriginalPciAttributesCount; >> ORDERED_COLLECTION *Tracker; >> UINTN *InstalledKey; >> INT32 Installed; >> @@ -595,10 +733,15 @@ InstallQemuFwCfgTables ( >> } >> >> // >> // first pass: process the commands >> // >> + // "WritePointerSubsetEnd" points one past the last successful >> + // QEMU_LOADER_WRITE_POINTER command. Now when we're about to start the first >> + // pass, no such command has been encountered yet. >> + // >> + WritePointerSubsetEnd = LoaderStart; >> for (LoaderEntry = LoaderStart; LoaderEntry < LoaderEnd; ++LoaderEntry) { >> switch (LoaderEntry->Type) { >> case QemuLoaderCmdAllocate: >> Status = ProcessCmdAllocate (&LoaderEntry->Command.Allocate, Tracker); >> break; >> @@ -611,25 +754,33 @@ InstallQemuFwCfgTables ( >> case QemuLoaderCmdAddChecksum: >> Status = ProcessCmdAddChecksum (&LoaderEntry->Command.AddChecksum, >> Tracker); >> break; >> >> + case QemuLoaderCmdWritePointer: >> + Status = ProcessCmdWritePointer (&LoaderEntry->Command.WritePointer, >> + Tracker); >> + if (!EFI_ERROR (Status)) { >> + WritePointerSubsetEnd = LoaderEntry + 1; >> + } >> + break; >> + >> default: >> DEBUG ((EFI_D_VERBOSE, "%a: unknown loader command: 0x%x\n", >> __FUNCTION__, LoaderEntry->Type)); >> break; >> } >> >> if (EFI_ERROR (Status)) { >> - goto FreeTracker; >> + goto RollbackWritePointersAndFreeTracker; >> } >> } >> >> InstalledKey = AllocatePool (INSTALLED_TABLES_MAX * sizeof *InstalledKey); >> if (InstalledKey == NULL) { >> Status = EFI_OUT_OF_RESOURCES; >> - goto FreeTracker; >> + goto RollbackWritePointersAndFreeTracker; >> } >> >> // >> // second pass: identify and install ACPI tables >> // >> @@ -656,11 +807,25 @@ InstallQemuFwCfgTables ( >> DEBUG ((EFI_D_INFO, "%a: installed %d tables\n", __FUNCTION__, Installed)); >> } >> >> FreePool (InstalledKey); >> >> -FreeTracker: >> +RollbackWritePointersAndFreeTracker: >> + // >> + // In case of failure, revoke any allocation addresses that were communicated >> + // to QEMU previously, before we release all the blobs. >> + // >> + if (EFI_ERROR (Status)) { >> + LoaderEntry = WritePointerSubsetEnd; >> + while (LoaderEntry > LoaderStart) { >> + --LoaderEntry; >> + if (LoaderEntry->Type == QemuLoaderCmdWritePointer) { >> + UndoCmdWritePointer (&LoaderEntry->Command.WritePointer); >> + } >> + } >> + } >> + >> // >> // Tear down the tracker infrastructure. Each fw_cfg blob will be left in >> // place only if we're exiting with success and the blob hosts data that is >> // not directly part of some ACPI table. >> // >> -- >> 2.9.3 >> >>