[v4] Fix overflow of the max number of IDs for logic processor and core

[PATCH v4 0/2] Fix overflow of the max number of IDs for logic processor and core

Posted by Qian Wen 8 months ago

CPUID.1.EBX[23:16]: Maximum number of addressable IDs for logical
processors in this physical package.
CPUID.4:EAX[31:26]: Maximum number of addressable IDs for processor cores
in the physical package.

The current qemu code doesn't limit the value written to these two fields.
If the guest has a huge number of cores, APs (application processor) will
fail to bring up and the wrong info will be reported.
According to HW behavior, setting max value written to CPUID.1.EBX[23:16]
to 255, and CPUID.4:EAX[31:26] to 63.

---
Changes v3 -> v4:
  - Add "Reviewed-by" from Isaku and Xiaoyao.
  - Rebase to the v8.1.0.
Changes v2 -> v3:
  - Add patch 2.
  - Revise the commit message and comment to be clearer.
  - Using MIN() for limitation.
Changes v1 -> v2:
  - Revise the commit message and comment to more clearer.
  - Rebased to v8.1.0-rc2.

Qian Wen (2):
  target/i386: Avoid cpu number overflow in legacy topology
  target/i386: Avoid overflow of the cache parameter enumerated by leaf
    4

 target/i386/cpu.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

base-commit:f5fe7c17ac4e309e47e78f0f9761aebc8d2f2c81
-- 
2.25.1

Re: [PATCH v4 0/2] Fix overflow of the max number of IDs for logic processor and core

Posted by Wen, Qian 7 months, 2 weeks ago

Kindly ping for any comments.

Thanks,
Qian

On 8/29/2023 12:24 PM, Qian Wen wrote:
> CPUID.1.EBX[23:16]: Maximum number of addressable IDs for logical
> processors in this physical package.
> CPUID.4:EAX[31:26]: Maximum number of addressable IDs for processor cores
> in the physical package.
>
> The current qemu code doesn't limit the value written to these two fields.
> If the guest has a huge number of cores, APs (application processor) will
> fail to bring up and the wrong info will be reported.
> According to HW behavior, setting max value written to CPUID.1.EBX[23:16]
> to 255, and CPUID.4:EAX[31:26] to 63.
>
> ---
> Changes v3 -> v4:
>   - Add "Reviewed-by" from Isaku and Xiaoyao.
>   - Rebase to the v8.1.0.
> Changes v2 -> v3:
>   - Add patch 2.
>   - Revise the commit message and comment to be clearer.
>   - Using MIN() for limitation.
> Changes v1 -> v2:
>   - Revise the commit message and comment to more clearer.
>   - Rebased to v8.1.0-rc2.
>
> Qian Wen (2):
>   target/i386: Avoid cpu number overflow in legacy topology
>   target/i386: Avoid overflow of the cache parameter enumerated by leaf
>     4
>
>  target/i386/cpu.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
>
> base-commit:f5fe7c17ac4e309e47e78f0f9761aebc8d2f2c81