On Wed, 26 Feb 2020 at 23:12, Laszlo Ersek <ler...@redhat.com> wrote:
>
> QEMU commit 3a61c8db9d25 ("acpi: cpuhp: add CPHP_GET_CPU_ID_CMD command",
> 2020-01-22) introduced a new command in the modern CPU hotplug register
> block that lets the firmware query the arch-specific IDs (on IA32/X64: the
> APIC IDs) of CPUs. Add a macro for this command value, because we'll need
> it later.
>
> At the same time, add a sanity check for the modern hotplug interface to
> CpuHotplugSmm.
>
> Cc: Ard Biesheuvel <ard.biesheu...@linaro.org>
> Cc: Igor Mammedov <imamm...@redhat.com>
> Cc: Jiewen Yao <jiewen....@intel.com>
> Cc: Jordan Justen <jordan.l.jus...@intel.com>
> Cc: Michael Kinney <michael.d.kin...@intel.com>
> Cc: Philippe Mathieu-Daudé <phi...@redhat.com>
> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1512
> Signed-off-by: Laszlo Ersek <ler...@redhat.com>
> Acked-by: Ard Biesheuvel <ard.biesheu...@linaro.org>
Reviewed-by: Ard Biesheuvel <ard.biesheu...@linaro.org>
> ---
>
> Notes:
> v2:
>
> - Pick up Ard's Acked-by, which is conditional on approval from Intel
> reviewers on Cc. (I'd like to save Ard the churn of re-acking
> unmodified patches.)
>
> OvmfPkg/Include/IndustryStandard/QemuCpuHotplug.h | 1 +
> OvmfPkg/CpuHotplugSmm/CpuHotplug.c | 35 ++++++++++++++++++++
> 2 files changed, 36 insertions(+)
>
> diff --git a/OvmfPkg/Include/IndustryStandard/QemuCpuHotplug.h
> b/OvmfPkg/Include/IndustryStandard/QemuCpuHotplug.h
> index cf0745610f2c..3d013633501b 100644
> --- a/OvmfPkg/Include/IndustryStandard/QemuCpuHotplug.h
> +++ b/OvmfPkg/Include/IndustryStandard/QemuCpuHotplug.h
> @@ -20,24 +20,25 @@
> #define QEMU_CPU_HOTPLUG_H_
>
> #include <Base.h>
>
> //
> // Each register offset is:
> // - relative to the board-dependent IO base address of the register block,
> // - named QEMU_CPUHP_(R|W|RW)_*, according to the possible access modes of
> the
> // register,
> // - followed by distinguished bitmasks or values in the register.
> //
> #define QEMU_CPUHP_R_CMD_DATA2 0x0
>
> #define QEMU_CPUHP_R_CPU_STAT 0x4
> #define QEMU_CPUHP_STAT_ENABLED BIT0
>
> #define QEMU_CPUHP_RW_CMD_DATA 0x8
>
> #define QEMU_CPUHP_W_CPU_SEL 0x0
>
> #define QEMU_CPUHP_W_CMD 0x5
> #define QEMU_CPUHP_CMD_GET_PENDING 0x0
> +#define QEMU_CPUHP_CMD_GET_ARCH_ID 0x3
>
> #endif // QEMU_CPU_HOTPLUG_H_
> diff --git a/OvmfPkg/CpuHotplugSmm/CpuHotplug.c
> b/OvmfPkg/CpuHotplugSmm/CpuHotplug.c
> index fd09403eabf3..5df8c689c63a 100644
> --- a/OvmfPkg/CpuHotplugSmm/CpuHotplug.c
> +++ b/OvmfPkg/CpuHotplugSmm/CpuHotplug.c
> @@ -1,38 +1,41 @@
> /** @file
> Root SMI handler for VCPU hotplug SMIs.
>
> Copyright (c) 2020, Red Hat, Inc.
>
> SPDX-License-Identifier: BSD-2-Clause-Patent
> **/
>
> #include <IndustryStandard/Q35MchIch9.h> // ICH9_APM_CNT
> +#include <IndustryStandard/QemuCpuHotplug.h> // QEMU_CPUHP_CMD_GET_PENDING
> #include <Library/BaseLib.h> // CpuDeadLoop()
> #include <Library/DebugLib.h> // ASSERT()
> #include <Library/MmServicesTableLib.h> // gMmst
> #include <Library/PcdLib.h> // PcdGetBool()
> #include <Protocol/MmCpuIo.h> // EFI_MM_CPU_IO_PROTOCOL
> #include <Uefi/UefiBaseType.h> // EFI_STATUS
>
> +#include "QemuCpuhp.h" // QemuCpuhpWriteCpuSelector()
> +
> //
> // We use this protocol for accessing IO Ports.
> //
> STATIC EFI_MM_CPU_IO_PROTOCOL *mMmCpuIo;
> //
> // Represents the registration of the CPU Hotplug MMI handler.
> //
> STATIC EFI_HANDLE mDispatchHandle;
>
>
> /**
> CPU Hotplug MMI handler function.
>
> This is a root MMI handler.
>
> @param[in] DispatchHandle The unique handle assigned to this handler
> by
> EFI_MM_SYSTEM_TABLE.MmiHandlerRegister().
>
> @param[in] Context Context passed in by
> EFI_MM_SYSTEM_TABLE.MmiManage(). Due to
> CpuHotplugMmi() being a root MMI handler,
> Context is ASSERT()ed to be NULL.
> @@ -149,43 +152,75 @@ CpuHotplugEntry (
> //
> // This driver depends on the dynamically detected "SMRAM at default
> SMBASE"
> // feature.
> //
> if (!PcdGetBool (PcdQ35SmramAtDefaultSmbase)) {
> return EFI_UNSUPPORTED;
> }
>
> //
> // Errors from here on are fatal; we cannot allow the boot to proceed if we
> // can't set up this driver to handle CPU hotplug.
> //
> // First, collect the protocols needed later. All of these protocols are
> // listed in our module DEPEX.
> //
> Status = gMmst->MmLocateProtocol (&gEfiMmCpuIoProtocolGuid,
> NULL /* Registration */, (VOID **)&mMmCpuIo);
> if (EFI_ERROR (Status)) {
> DEBUG ((DEBUG_ERROR, "%a: locate MmCpuIo: %r\n", __FUNCTION__, Status));
> goto Fatal;
> }
>
> + //
> + // Sanity-check the CPU hotplug interface.
> + //
> + // Both of the following features are part of QEMU 5.0, introduced
> primarily
> + // in commit range 3e08b2b9cb64..3a61c8db9d25:
> + //
> + // (a) the QEMU_CPUHP_CMD_GET_ARCH_ID command of the modern CPU hotplug
> + // interface,
> + //
> + // (b) the "SMRAM at default SMBASE" feature.
> + //
> + // From these, (b) is restricted to 5.0+ machine type versions, while (a)
> + // does not depend on machine type version. Because we ensured the stricter
> + // condition (b) through PcdQ35SmramAtDefaultSmbase above, the (a)
> + // QEMU_CPUHP_CMD_GET_ARCH_ID command must now be available too. While we
> + // can't verify the presence of precisely that command, we can still verify
> + // (sanity-check) that the modern interface is active, at least.
> + //
> + // Consult the "Typical usecases | Detecting and enabling modern CPU
> hotplug
> + // interface" section in QEMU's "docs/specs/acpi_cpu_hotplug.txt", on the
> + // following.
> + //
> + QemuCpuhpWriteCpuSelector (mMmCpuIo, 0);
> + QemuCpuhpWriteCpuSelector (mMmCpuIo, 0);
> + QemuCpuhpWriteCommand (mMmCpuIo, QEMU_CPUHP_CMD_GET_PENDING);
> + if (QemuCpuhpReadCommandData2 (mMmCpuIo) != 0) {
> + Status = EFI_NOT_FOUND;
> + DEBUG ((DEBUG_ERROR, "%a: modern CPU hotplug interface: %r\n",
> + __FUNCTION__, Status));
> + goto Fatal;
> + }
> +
> //
> // Register the handler for the CPU Hotplug MMI.
> //
> Status = gMmst->MmiHandlerRegister (
> CpuHotplugMmi,
> NULL, // HandlerType: root MMI handler
> &mDispatchHandle
> );
> if (EFI_ERROR (Status)) {
> DEBUG ((DEBUG_ERROR, "%a: MmiHandlerRegister(): %r\n", __FUNCTION__,
> Status));
> goto Fatal;
> }
>
> return EFI_SUCCESS;
>
> Fatal:
> ASSERT (FALSE);
> CpuDeadLoop ();
> return Status;
> }
> --
> 2.19.1.3.g30247aa5d201
>
>
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