From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57652) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WSl73-0006Zq-SY for qemu-devel@nongnu.org; Wed, 26 Mar 2014 06:31:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WSl6x-0007mc-RC for qemu-devel@nongnu.org; Wed, 26 Mar 2014 06:31:13 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41130) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WSl6x-0007mW-JR for qemu-devel@nongnu.org; Wed, 26 Mar 2014 06:31:07 -0400 Date: Wed, 26 Mar 2014 12:31:12 +0200 From: "Michael S. Tsirkin" Message-ID: <20140326103112.GA20219@redhat.com> References: <20140326064510.5518.72436.malonedeb@chaenomeles.canonical.com> <20140326064510.5518.72436.malonedeb@chaenomeles.canonical.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20140326064510.5518.72436.malonedeb@chaenomeles.canonical.com> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [Bug 1297651] [NEW] KVM create a win7 guest with Qemu, it boots up fail List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Bug 1297651 <1297651@bugs.launchpad.net> Cc: robert.hu@intel.com, lersek@redhat.com, qemu-devel@nongnu.org, ehabkost@redhat.com On Wed, Mar 26, 2014 at 06:45:10AM -0000, Robert Hu wrote: > Public bug reported: >=20 > Environment: > ------------ > Host OS (ia32/ia32e/IA64):ia32e > Guest OS (ia32/ia32e/IA64):ia32e > Guest OS Type (Linux/Windows):Windows > kvm.git Commit:94b3ffcd41a90d2cb0b32ca23aa58a01111d5dc0 > qemu-kvm Commit:839a5547574e57cce62f49bfc50fe1f04b00589a > Host Kernel Version:3.14.0-rc3 > Hardware:Romley_EP, Ivytown_EP, HSW_EP >=20 >=20 > Bug detailed description: > -------------------------- > when create a win7 guest, the guest boot up fail. >=20 > note:=20 > 1. when create win2000, winxp, win2k3, win2k8, guest, the guest boot up= fail. > 2. when create win8, win8.1, win2012 guest, the guest boot up fine. >=20 >=20 > Reproduce steps: > ---------------- > 1.create guest > qemu-system-x86_64 -enable-kvm -m 1024 -smp 2 -net none -hda /root/win7= .qcow >=20 >=20 > Current result: > ---------------- > win7 guest boot up fail >=20 > Expected result: > ---------------- > win7 guest boot up fine >=20 > Basic root-causing log: > ---------------------- >=20 > This should be a qemu bug > kvm + qemu =3D result > 94b3ffcd + 839a5547 =3D bad > 94b3ffcd + 3a87f8b6 =3D good >=20 > the first bad commit is: > commit 9bcc80cd71892df42605e0c097d85c0237ff45d1 > Author: Laszlo Ersek Thanks for the excellent bug report! > Date: Mon Mar 17 17:05:16 2014 +0100 >=20 > i386/acpi-build: allow more than 255 elements in CPON >=20 > The build_ssdt() function builds a number of AML objects that are r= elated > to CPU hotplug, and whose IDs form a contiguous sequence of APIC ID= s. > (APIC IDs are in fact discontiguous, but this is the traditional > interface: build a contiguous sequence from zero up that covers all > possible APIC IDs.) These objects are: >=20 > - a Processor() object for each VCPU, > - a NTFY method, with one branch for each VCPU, > - a CPON package with one element (hotplug status byte) for each VC= PU. >=20 > The build_ssdt() function currently limits the *count* of processor > objects, and NTFY branches, and CPON elements, in 0xFF (see the ass= ignment > to "acpi_cpus"). This allows for an inclusive APIC ID range of [0..= 254]. > This is incorrect, because the highest APIC ID that we otherwise al= low a > VCPU to take is 255. >=20 > In order to extend the maximum count to 256, and the traversed APIC= ID > range correspondingly to [0..255]: > - the Processor() objects need no change, > - the NTFY method also needs no change, > - the CPON package must be updated, because it is defined with a > DefPackage, and the number of elements in such a package can be a= t most > 255. We pick a DefVarPackage instead. >=20 > We replace the Op byte, and the encoding of the number of elements. > Compare: >=20 > DefPackage :=3D PackageOp PkgLength NumElements PackageEl= ementList > DefVarPackage :=3D VarPackageOp PkgLength VarNumElements PackageEl= ementList >=20 > PackageOp :=3D 0x12 > VarPackageOp :=3D 0x13 I think I know what's going on here: the specification says: The ASL compiler can emit two different AML opcodes for a Package declaration, either PackageOp or VarPackageOp. For small, fixed-length packages, the PackageOp is used and this opcode is compatible with ACPI 1.0. A VarPackageOp will be emitted if any of the following conditions are true: =E2=80=A2 The NumElements argument is a TermArg that can only be resolved at runtime. =E2=80=A2 At compile time, NumElements resolves to a constant that is larger than 255. =E2=80=A2 The PackageList contains more than 255 initializer elements. So we clearly violate this rule. > NumElements :=3D ByteData > VarNumElements :=3D TermArg =3D> Integer >=20 > The build_append_int() function implements precisely the following = TermArg > encodings (a subset of what the ACPI spec describes): >=20 > TermArg :=3D DataObject > DataObject :=3D ComputationalData > ComputationalData :=3D ConstObj | ByteConst | WordConst | DWord= Const > directly encoded in the function, with build_append_byte(): > ConstObj :=3D ZeroOp | OneOp > ZeroOp :=3D 0x00 > OneOp :=3D 0x01 >=20 > call to build_append_value(..., 1): > ByteConst :=3D BytePrefix ByteData > BytePrefix :=3D 0x0A > ByteData :=3D 0x00 - 0xFF >=20 > call to build_append_value(..., 2): > WordConst :=3D WordPrefix WordData > WordPrefix :=3D 0x0B > WordData :=3D ByteData[0:7] ByteData[8:15] >=20 > call to build_append_value(..., 4): > DWordConst :=3D DWordPrefix DWordData > DWordPrefix :=3D 0x0C > DWordData :=3D WordData[0:15] WordData[16:31] >=20 > Signed-off-by: Laszlo Ersek > Reviewed-by: Michael S. Tsirkin > Signed-off-by: Michael S. Tsirkin >=20 > ** Affects: qemu > Importance: Undecided > Status: New > The following seems to fix the issue - still testing. Can you confirm ple= ase? However the question we should ask is whether it's a good idea to allow hotplug ID values that might make guests fail to boot. How about limiting ACPI_CPU_HOTPLUG_ID_LIMIT to 255? We never allowed > 255 in the past, is it worth the maintainance headaches? =20 diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c index f1054dd..7597517 100644 --- a/hw/i386/acpi-build.c +++ b/hw/i386/acpi-build.c @@ -1055,9 +1055,21 @@ build_ssdt(GArray *table_data, GArray *linker, =20 { GArray *package =3D build_alloc_array(); - uint8_t op =3D 0x13; /* VarPackageOp */ + uint8_t op; + + /* + * Note: The ability to create variable-sized packages was f= irst introduced in ACPI 2.0. ACPI 1.0 only + * allowed fixed-size packages with up to 255 elements. + * Windows guests up to win2k8 fail when VarPackageOp is use= d. + */ + if (acpi_cpus <=3D 255) { + op =3D 0x12; /* PackageOp */ + build_append_byte(package, acpi_cpus); /* NumElements */ + } else { + op =3D 0x13; /* VarPackageOp */ + build_append_int(package, acpi_cpus); /* VarNumElements = */ + } =20 - build_append_int(package, acpi_cpus); /* VarNumElements */ for (i =3D 0; i < acpi_cpus; i++) { uint8_t b =3D test_bit(i, cpu->found_cpus) ? 0x01 : 0x00= ; build_append_byte(package, b);