From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44786) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YHu4f-00039K-Bt for qemu-devel@nongnu.org; Sun, 01 Feb 2015 07:56:31 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YHu4Y-000277-14 for qemu-devel@nongnu.org; Sun, 01 Feb 2015 07:56:25 -0500 Received: from mx1.redhat.com ([209.132.183.28]:48029) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YHu4X-000273-P0 for qemu-devel@nongnu.org; Sun, 01 Feb 2015 07:56:17 -0500 Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id t11CuGA0027201 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL) for ; Sun, 1 Feb 2015 07:56:16 -0500 Message-ID: <54CE227A.9020000@redhat.com> Date: Sun, 01 Feb 2015 14:56:26 +0200 From: Gal Hammer MIME-Version: 1.0 References: <1418745044-3986-1-git-send-email-ghammer@redhat.com> <1418745044-3986-3-git-send-email-ghammer@redhat.com> <20150122145246.5d020fab@nial.brq.redhat.com> In-Reply-To: <20150122145246.5d020fab@nial.brq.redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH V11 2/3] i386: Add a Virtual Machine Generation ID device List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Igor Mammedov Cc: qemu-devel@nongnu.org, mst@redhat.com On 22/01/2015 15:52, Igor Mammedov wrote: > On Tue, 16 Dec 2014 17:50:43 +0200 > Gal Hammer wrote: > >> Based on Microsoft's sepecifications (paper can be dowloaded from >> http://go.microsoft.com/fwlink/?LinkId=260709), add a device >> description to the SSDT ACPI table and its implementation. >> >> The GUID is set using a global "vmgenid.uuid" parameter. >> >> Signed-off-by: Gal Hammer >> > >> --- a/hw/i386/acpi-build.c >> +++ b/hw/i386/acpi-build.c >> @@ -257,6 +257,7 @@ static void acpi_get_pci_info(PcPciInfo *info) >> #define ACPI_BUILD_TABLE_FILE "etc/acpi/tables" >> #define ACPI_BUILD_RSDP_FILE "etc/acpi/rsdp" >> #define ACPI_BUILD_TPMLOG_FILE "etc/tpm/log" >> +#define ACPI_BUILD_VMGENID_FILE "etc/vm-generation-id" >> >> static void >> build_header(GArray *linker, GArray *table_data, >> @@ -1068,6 +1069,8 @@ build_ssdt(GArray *table_data, GArray *linker, >> { >> MachineState *machine = MACHINE(qdev_get_machine()); >> uint32_t nr_mem = machine->ram_slots; >> + uint32_t vm_gid_physical_address; >> + uint32_t vm_gid_offset = 0; >> unsigned acpi_cpus = guest_info->apic_id_limit; >> int ssdt_start = table_data->len; >> uint8_t *ssdt_ptr; >> @@ -1096,6 +1099,21 @@ build_ssdt(GArray *table_data, GArray *linker, >> ACPI_BUILD_SET_LE(ssdt_ptr, sizeof(ssdp_misc_aml), >> ssdt_isa_pest[0], 16, misc->pvpanic_port); >> >> + if (vm_generation_id_set()) { >> + vm_gid_physical_address = ssdt_start + ssdt_acpi_vm_gid_addr[0]; >> + bios_linker_loader_alloc(linker, ACPI_BUILD_VMGENID_FILE, 8, true); >> + bios_linker_loader_add_pointer(linker, ACPI_BUILD_VMGENID_FILE, >> + ACPI_BUILD_TABLE_FILE, >> + table_data, >> + &vm_gid_offset, >> + sizeof(vm_gid_offset)); > could some explain how this pointer magic works, I can try, but don't you think that a magic is gone once explained? ;-) > From my weak understanding it seems broken. > Lets see: > > [1] &vm_gid_offset - must be pointer inside of dest_file blob (ACPI_BUILD_VMGENID_FILE) > [2] vm_gid_offset - should hold offset of the place inside of src_file > (ACPI_BUILD_TABLE_FILE) where to pointer inside of dest_file should point to The vm_gid_offset should point where in the ACPI_BUILD_VMGENID_FILE the VM's GUID is stored. At the moment, it should always be zero because the GUID is stored at the begging of the ACPI_BUILD_VMGENID_FILE. > > now: > vm_gid_physical_address - holds [2] i.e. offset of VGIA constant in inside SSDT in ACPI_BUILD_TABLE_FILE. > >> + ACPI_BUILD_SET_LE(ssdt_ptr, sizeof(ssdp_misc_aml), >> + ssdt_acpi_vm_gid_addr[0], 32, vm_gid_physical_address); > Then we write this offset into VGIA in ACPI_BUILD_TABLE_FILE. Yes. This offset is later patched by the linker to the full physical address. > After BIOS loads tables it's going to patch at > [3] ACPI_BUILD_VMGENID_FILE + (&vm_gid_offset - table_data->data) /* only god knows where it will be/ > > and on top of it write in it value: > *(ACPI_BUILD_TABLE_FILE + *[3]) We know exactly where it is, no need to call for god's help :-). > This approach in general of patching arbitrary place in AML blob > to get PHY addr of buffer with UUID, is quite a hack, especially > in light of that we are trying to hide all direct access to AML > blobs with related pointer arithmetic and manual patching. > > Why not reserve some potion of RAM and pass to BIOS/guest > a reservation so it won't be part of AddressRangeMemory or > AddressRangeACPI as MS spec requires? Then you won't need > jump all above hoops to just get buffer's PHY addr. I'll be glad to hear a new idea that I didn't already try in one of other previous patches. The problem is that the specification requires working with a physical address, so it must be allocated from inside the guest. Since the OS is not exist in this stage and I also don't want to write a special driver just to allocate this buffer I had to choose this approach. >> > [...] >> typedef >> @@ -1790,6 +1811,11 @@ void acpi_setup(PcGuestInfo *guest_info) >> fw_cfg_add_file(guest_info->fw_cfg, ACPI_BUILD_TPMLOG_FILE, >> tables.tcpalog->data, acpi_data_len(tables.tcpalog)); >> >> + /* Add a 128-bit fw cfg file which stores the VM generation id. */ >> + g_array_set_size(tables.vmgenid, 16); >> + fw_cfg_add_file(guest_info->fw_cfg, ACPI_BUILD_VMGENID_FILE, >> + tables.vmgenid->data, tables.vmgenid->len); > shouldn't it be migratable? /i.e. acpi_add_rom_blob(...)/ > I'm not too familiar with the migration process, but I assume that this memory will be copied as part of the guest memory. Gal.