Re: [PATCH v9 00/10] support CPU hot-unplug

["Ankur Arora" <ankur.a.arora@oracle.com>]

On 2021-03-16 7:07 a.m., Laszlo Ersek wrote:
> On 03/12/21 07:26, Ankur Arora wrote:
>> Hi,
>>
>> This series adds OVMF support for CPU hot-unplug.
>>
>> QEMU secureboot hot-unplug logic corresponding to this is in upstream.
>> Also posted here:
>>    https://lore.kernel.org/qemu-devel/20201207140739.3829993-1-imammedo@redhat.com/
>>
>> Testing (with QEMU 5.2.50):
>>   - Stable with randomized CPU plug/unplug (guest maxcpus=33,128)
>>   - Synthetic tests with simultaneous multi CPU hot-unplug
>>
>> Also at:
>>    github.com/terminus/edk2/ hot-unplug-v9
>>
>> Changelog:
>>
>> v9:
>>    - Rebased on top of edd46cd407ea
>>    - Clarify comments around memory-barriers in patches 7, 8, 9
>>    - Address other review comments from v8
> 
> Merged as commit range 4751a48aeb2a..f3bdfc41866e, via
> <https://github.com/tianocore/edk2/pull/1494>, with the following R-b's
> / comments / light tweaks added:

Awesome! Thanks Laszlo.

And, thanks especially for the thorough reviews.

Ankur

> 
>>   1:  4b4466ed7c44 =  1:  0cb242e33693 OvmfPkg/CpuHotplugSmm: refactor hotplug logic
>>   2:  719828efdebe !  2:  a752dd07466c OvmfPkg/CpuHotplugSmm: collect hot-unplug events
>>      @@ -20,6 +20,7 @@
>>           Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3132
>>           Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
>>           Message-Id: <20210312062656.2477515-3-ankur.a.arora@oracle.com>
>>      +    Reviewed-by: Laszlo Ersek <lersek@redhat.com>
>>
>>       diff --git a/OvmfPkg/Include/IndustryStandard/QemuCpuHotplug.h b/OvmfPkg/Include/IndustryStandard/QemuCpuHotplug.h
>>       --- a/OvmfPkg/Include/IndustryStandard/QemuCpuHotplug.h
>>   3:  7d732efcb7af =  3:  2d92e052c3af OvmfPkg/CpuHotplugSmm: add Qemu Cpu Status helper
>>   4:  64649eeeee42 =  4:  15e6ae8ea400 OvmfPkg/CpuHotplugSmm: introduce UnplugCpus()
>>   5:  7190a5d134a7 !  5:  8ade9d425a6e OvmfPkg: define CPU_HOT_EJECT_DATA
>>      @@ -15,6 +15,7 @@
>>           Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3132
>>           Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
>>           Message-Id: <20210312062656.2477515-6-ankur.a.arora@oracle.com>
>>      +    Reviewed-by: Laszlo Ersek <lersek@redhat.com>
>>
>>       diff --git a/OvmfPkg/OvmfPkg.dec b/OvmfPkg/OvmfPkg.dec
>>       --- a/OvmfPkg/OvmfPkg.dec
>>   6:  1fd019dac476 !  6:  b6d5996706dd OvmfPkg/SmmCpuFeaturesLib: init CPU ejection state
>>      @@ -22,6 +22,7 @@
>>           Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3132
>>           Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
>>           Message-Id: <20210312062656.2477515-7-ankur.a.arora@oracle.com>
>>      +    Reviewed-by: Laszlo Ersek <lersek@redhat.com>
>>
>>       diff --git a/OvmfPkg/Library/SmmCpuFeaturesLib/SmmCpuFeaturesLib.inf b/OvmfPkg/Library/SmmCpuFeaturesLib/SmmCpuFeaturesLib.inf
>>       --- a/OvmfPkg/Library/SmmCpuFeaturesLib/SmmCpuFeaturesLib.inf
>>   7:  c8758d9b9764 !  7:  af9c77e151fa OvmfPkg/SmmCpuFeaturesLib: call CPU hot-eject handler
>>      @@ -19,6 +19,7 @@
>>           Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3132
>>           Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
>>           Message-Id: <20210312062656.2477515-8-ankur.a.arora@oracle.com>
>>      +    Reviewed-by: Laszlo Ersek <lersek@redhat.com>
>>
>>       diff --git a/OvmfPkg/Library/SmmCpuFeaturesLib/SmmCpuFeaturesLib.c b/OvmfPkg/Library/SmmCpuFeaturesLib/SmmCpuFeaturesLib.c
>>       --- a/OvmfPkg/Library/SmmCpuFeaturesLib/SmmCpuFeaturesLib.c
>>   8:  5ff8e8700678 !  8:  30c69d2cfa63 OvmfPkg/CpuHotplugSmm: add EjectCpu()
>>      @@ -19,6 +19,7 @@
>>           Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3132
>>           Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
>>           Message-Id: <20210312062656.2477515-9-ankur.a.arora@oracle.com>
>>      +    Reviewed-by: Laszlo Ersek <lersek@redhat.com>
>>
>>       diff --git a/OvmfPkg/CpuHotplugSmm/CpuHotplugSmm.inf b/OvmfPkg/CpuHotplugSmm/CpuHotplugSmm.inf
>>       --- a/OvmfPkg/CpuHotplugSmm/CpuHotplugSmm.inf
>>   9:  d6660f8f2f14 !  9:  f05328886302 OvmfPkg/CpuHotplugSmm: do actual CPU hot-eject
>>      @@ -27,6 +27,9 @@
>>           Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3132
>>           Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
>>           Message-Id: <20210312062656.2477515-10-ankur.a.arora@oracle.com>
>>      +    Reviewed-by: Laszlo Ersek <lersek@redhat.com>
>>      +    [lersek@redhat.com: unneeded inner QemuSelector declaration in EjectCpu()
>>      +     triggers VS warning #4456 (local variable shadowed); remove it]
>>
>>       diff --git a/OvmfPkg/Include/IndustryStandard/QemuCpuHotplug.h b/OvmfPkg/Include/IndustryStandard/QemuCpuHotplug.h
>>       --- a/OvmfPkg/Include/IndustryStandard/QemuCpuHotplug.h
>>      @@ -102,8 +105,6 @@
>>       +    UINT32 Idx;
>>       +
>>       +    for (Idx = 0; Idx < mCpuHotEjectData->ArrayLength; Idx++) {
>>      -+      UINT64 QemuSelector;
>>      -+
>>       +      QemuSelector = mCpuHotEjectData->QemuSelectorMap[Idx];
>>       +
>>       +      if (QemuSelector != CPU_EJECT_QEMU_SELECTOR_INVALID) {
>> 10:  0a9a1cd40b98 ! 10:  f3bdfc41866e OvmfPkg/SmmControl2Dxe: negotiate CPU hot-unplug
>>      @@ -14,6 +14,9 @@
>>           Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3132
>>           Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
>>           Message-Id: <20210312062656.2477515-11-ankur.a.arora@oracle.com>
>>      +    [lersek@redhat.com: preserve the empty line between the ICH9_LPC_SMI_F_*
>>      +     group of macro definitions and the SCRATCH_BUFFER type definition]
>>      +    Reviewed-by: Laszlo Ersek <lersek@redhat.com>
>>
>>       diff --git a/OvmfPkg/SmmControl2Dxe/SmiFeatures.c b/OvmfPkg/SmmControl2Dxe/SmiFeatures.c
>>       --- a/OvmfPkg/SmmControl2Dxe/SmiFeatures.c
>>      @@ -22,16 +25,15 @@
>>        // "etc/smi/supported-features" and "etc/smi/requested-features" fw_cfg files.
>>        //
>>        #define ICH9_LPC_SMI_F_CPU_HOTPLUG BIT1
>>      --
>>       +//
>>       +// The following bit value stands for "enable CPU hot-unplug, and inject an SMI
>>       +// with control value ICH9_APM_CNT_CPU_HOTPLUG upon hot-unplug", in the
>>       +// "etc/smi/supported-features" and "etc/smi/requested-features" fw_cfg files.
>>       +//
>>       +#define ICH9_LPC_SMI_F_CPU_HOT_UNPLUG BIT2
>>      +
>>        //
>>        // Provides a scratch buffer (allocated in EfiReservedMemoryType type memory)
>>      - // for the S3 boot script fragment to write to and read from.
>>       @@
>>          QemuFwCfgReadBytes (sizeof mSmiFeatures, &mSmiFeatures);
>>
> 
> Thanks for the contribution,
> Laszlo
>