From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51037) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cTEb1-0005Vz-Su for qemu-devel@nongnu.org; Mon, 16 Jan 2017 16:13:45 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cTEay-0001h3-K2 for qemu-devel@nongnu.org; Mon, 16 Jan 2017 16:13:43 -0500 Received: from mx1.redhat.com ([209.132.183.28]:50044) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cTEay-0001gL-CB for qemu-devel@nongnu.org; Mon, 16 Jan 2017 16:13:40 -0500 References: <1484328738-21149-1-git-send-email-ard.biesheuvel@linaro.org> From: Laszlo Ersek Message-ID: Date: Mon, 16 Jan 2017 22:13:36 +0100 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v2] hw/arm/virt-acpi - reserve ECAM space as PNP0C02 device List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Ard Biesheuvel , Peter Maydell Cc: Leif Lindholm , Andrew Jones , QEMU Developers , Graeme Gregory , Al Stone On 01/16/17 20:31, Ard Biesheuvel wrote: > On 16 January 2017 at 18:20, Peter Maydell wrote: >> On 16 January 2017 at 17:30, Ard Biesheuvel wrote: >>> On 16 January 2017 at 17:25, Peter Maydell wrote: >>>> On 13 January 2017 at 17:32, Ard Biesheuvel wrote: >>>>> Linux for arm64 v4.10 and later will complain if the ECAM config space is >>>>> not reserved in the ACPI namespace: >>>>> >>>>> acpi PNP0A08:00: [Firmware Bug]: ECAM area [mem 0x3f000000-0x3fffffff] not reserved in ACPI namespace >>>>> >>>>> The rationale is that OSes that don't consume the MCFG table should still >>>>> be able to infer that the PCI config space MMIO region is occupied. >>>>> >>>>> So update the ACPI table generation routine to add this reservation. >>>>> >>>>> Signed-off-by: Ard Biesheuvel >>>>> --- >>>>> hw/arm/virt-acpi-build.c | 7 +++++++ >>>>> 1 file changed, 7 insertions(+) >>>>> >>>>> diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c >>>>> index 085a61117378..50d52f685f68 100644 >>>>> --- a/hw/arm/virt-acpi-build.c >>>>> +++ b/hw/arm/virt-acpi-build.c >>>>> @@ -310,6 +310,13 @@ static void acpi_dsdt_add_pci(Aml *scope, const MemMapEntry *memmap, >>>>> Aml *dev_rp0 = aml_device("%s", "RP0"); >>>>> aml_append(dev_rp0, aml_name_decl("_ADR", aml_int(0))); >>>>> aml_append(dev, dev_rp0); >>>>> + >>>>> + Aml *dev_res0 = aml_device("%s", "RES0"); >>>>> + aml_append(dev_res0, aml_name_decl("_HID", aml_string("PNP0C02"))); >>>>> + crs = aml_resource_template(); >>>>> + aml_append(crs, aml_memory32_fixed(base_ecam, size_ecam, AML_READ_WRITE)); >>>>> + aml_append(dev_res0, aml_name_decl("_CRS", crs)); >>>>> + aml_append(dev, dev_res0); >>>>> aml_append(scope, dev); >>>>> } >>>> >>>> This needs to be controlled via the machine class back-compat >>>> machinery in hw/arm/virt.c so that it only happens for virt-2.9 >>>> and later. >>>> >>> >>> Why exactly? >> >> Because the "virt-2.8" machine has to present to the guest >> exactly what "virt" did as of the QEMU 2.8 release, including >> any bugs or missing things we happened to have in our ACPI >> tables. This allows cross-version compatibility (including >> VM migration). Drew will have a more detailed explanation >> if you need it. >> > > I suspected as much. > > But in this case, I am not sure if it is worth the trouble: the > generated data is only consumed at boot time by the firmware, and I > suppose migration involves freezing a VM, including whatever resident > firmware image was used to boot the OS, and so this is unlikely to > affect migration. > > But I will let Drew explain ... The PCI Firmware Specification (rev 3.1) says in 4.1.2. "MCFG Table Description": "The resources can *optionally* be returned in [...] EFIGetMemoryMap as reserved memory [...]". (Emphasis mine.) Linux seems to *insist* on this kind of reservation however. PNP0C02 is "General ID for reserving resources required by PnP motherboard registers. (Not device specific.)", according to . So what this patch does is reserve a memory area through ACPI, practically as an unspecified "platform resource". There's an alternative that's contained entirely in the firmware. You can cover the MMCONFIG area in ArmVirtQemu with an EfiReservedMemoryType memory map entry (by producing an appropriate memalloc HOB in PEI, or by calling the appropriate gDS memory space map functions in DXE). OVMF does the former (memalloc HOB). In ArmVirtQemu, we grab the MMCONFIG range from "pci-host-ecam-generic", from QEMU's DTB. If you don't dislike the idea, we could cover the range as well, right in "ArmVirtPkg/Library/FdtPciPcdProducerLib". That lib instance already sets the base address PCD, and makes sure that the relevant code is executed only once (in whatever driver module the library instance was built into). You could call the gDS functions mentioned above from that spot. (The library instance is already restricted to DXE_DRIVER and UEFI_DRIVER modules.) Thanks! Laszlo