On 10/20/15 22:09, Janusz wrote:
> W dniu 20.10.2015 o 21:27, Laszlo Ersek pisze:
>> Due to Linux kernel commit b18d5431acc7 ("KVM: x86: fix CR0.CD
>> virtualization"), vCPUs need more time to start up, because:
>>
>> - KVM now zaps all the mappings for the guest memory in EPT or shadow page
>> table, hence more VM exits are required to rebuild the mappings for all
>> memory accesses.
>>
>> - If a physical device has been assigned to the guest, and the IOMMU lacks
>> the snoop control feature, guest memory will become uncacheable after
>> CR0.CD is set to 1.
>>
>> UefiCpuPkg/UefiCpuPkg.dec sets the timeout to 50ms; startup failures with
>> 100ms have been reported. Xiao Guangrong suggested 1s, and helped word the
>> commit message.
>>
>> Cc: Xiao Guangrong <guangrong.x...@linux.intel.com>
>> Cc: Jordan Justen <jordan.l.jus...@intel.com>
>> Cc: Janusz Mocek <janusz...@gmail.com>
>> Cc: Alex Williamson <alex.william...@redhat.com>
>> Reported-by: Janusz Mocek <janusz...@gmail.com>
>> Suggested-by: Xiao Guangrong <guangrong.x...@linux.intel.com>
>> Contributed-under: TianoCore Contribution Agreement 1.0
>> Signed-off-by: Laszlo Ersek <ler...@redhat.com>
>> ---
>> OvmfPkg/OvmfPkgIa32.dsc | 6 ++++++
>> OvmfPkg/OvmfPkgIa32X64.dsc | 8 +++++++-
>> OvmfPkg/OvmfPkgX64.dsc | 6 ++++++
>> 3 files changed, 19 insertions(+), 1 deletion(-)
>>
>> diff --git a/OvmfPkg/OvmfPkgIa32.dsc b/OvmfPkg/OvmfPkgIa32.dsc
>> index 0d044c2..670a80f 100644
>> --- a/OvmfPkg/OvmfPkgIa32.dsc
>> +++ b/OvmfPkg/OvmfPkgIa32.dsc
>> @@ -358,6 +358,12 @@ [PcdsFixedAtBuild]
>> gEfiSourceLevelDebugPkgTokenSpaceGuid.PcdDebugLoadImageMethod|0x2
>> !endif
>>
>> + # Initial AP detection may take a long time on KVM; dependent on device
>> + # assignment, IOMMU features, VCPU count, and more. Allow a generous
>> interval
>> + # for the MP services initialization in UefiCpuPkg/CpuDxe to count the
>> APs,
>> + # and to wait until they become idle again.
>> + gUefiCpuPkgTokenSpaceGuid.PcdCpuApInitTimeOutInMicroSeconds|1000000
>> +
>> !ifndef $(USE_OLD_SHELL)
>> gEfiIntelFrameworkModulePkgTokenSpaceGuid.PcdShellFile|{ 0x83, 0xA5,
>> 0x04, 0x7C, 0x3E, 0x9E, 0x1C, 0x4F, 0xAD, 0x65, 0xE0, 0x52, 0x68, 0xD0,
>> 0xB4, 0xD1 }
>> !endif
>> diff --git a/OvmfPkg/OvmfPkgIa32X64.dsc b/OvmfPkg/OvmfPkgIa32X64.dsc
>> index 19d2221..8c00096 100644
>> --- a/OvmfPkg/OvmfPkgIa32X64.dsc
>> +++ b/OvmfPkg/OvmfPkgIa32X64.dsc
>> @@ -51,7 +51,7 @@ [BuildOptions]
>>
>> [BuildOptions.common.EDKII.DXE_RUNTIME_DRIVER]
>> GCC:*_*_*_DLINK_FLAGS = -z common-page-size=0x1000
>> -
>> +
>>
>> ################################################################################
>> #
>> # SKU Identification section - list of all SKU IDs supported by this
>> Platform.
>> @@ -363,6 +363,12 @@ [PcdsFixedAtBuild]
>> gEfiSourceLevelDebugPkgTokenSpaceGuid.PcdDebugLoadImageMethod|0x2
>> !endif
>>
>> + # Initial AP detection may take a long time on KVM; dependent on device
>> + # assignment, IOMMU features, VCPU count, and more. Allow a generous
>> interval
>> + # for the MP services initialization in UefiCpuPkg/CpuDxe to count the
>> APs,
>> + # and to wait until they become idle again.
>> + gUefiCpuPkgTokenSpaceGuid.PcdCpuApInitTimeOutInMicroSeconds|1000000
>> +
>> !ifndef $(USE_OLD_SHELL)
>> gEfiIntelFrameworkModulePkgTokenSpaceGuid.PcdShellFile|{ 0x83, 0xA5,
>> 0x04, 0x7C, 0x3E, 0x9E, 0x1C, 0x4F, 0xAD, 0x65, 0xE0, 0x52, 0x68, 0xD0,
>> 0xB4, 0xD1 }
>> !endif
>> diff --git a/OvmfPkg/OvmfPkgX64.dsc b/OvmfPkg/OvmfPkgX64.dsc
>> index b8df1dc..eb4da4f 100644
>> --- a/OvmfPkg/OvmfPkgX64.dsc
>> +++ b/OvmfPkg/OvmfPkgX64.dsc
>> @@ -363,6 +363,12 @@ [PcdsFixedAtBuild]
>> gEfiSourceLevelDebugPkgTokenSpaceGuid.PcdDebugLoadImageMethod|0x2
>> !endif
>>
>> + # Initial AP detection may take a long time on KVM; dependent on device
>> + # assignment, IOMMU features, VCPU count, and more. Allow a generous
>> interval
>> + # for the MP services initialization in UefiCpuPkg/CpuDxe to count the
>> APs,
>> + # and to wait until they become idle again.
>> + gUefiCpuPkgTokenSpaceGuid.PcdCpuApInitTimeOutInMicroSeconds|1000000
>> +
>> !ifndef $(USE_OLD_SHELL)
>> gEfiIntelFrameworkModulePkgTokenSpaceGuid.PcdShellFile|{ 0x83, 0xA5,
>> 0x04, 0x7C, 0x3E, 0x9E, 0x1C, 0x4F, 0xAD, 0x65, 0xE0, 0x52, 0x68, 0xD0,
>> 0xB4, 0xD1 }
>> !endif
> Tested-by: Janusz Mocek <janusz...@gmail.com>
>
> Thanks
>
Thanks for testing it. We'll need a better design (see the discussion
with Jordan), but until we implement that in upstream, we can perhaps
ask Gerd to add this patch to his RPMs -- this should work as a
short-term band-aid for assigned GPU users.
For upstream, Jordan's suggestion is clearly superior, so we shall do
that; once ready, this patch can be backed out of Gerd's build.
Thanks
Laszlo
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