Hi Chuang,
On Mon, May 27, 2024 at 11:13:33AM +0800, Chuang Xu wrote:
> Date: Mon, 27 May 2024 11:13:33 +0800
> From: Chuang Xu <xuchuangxc...@bytedance.com>
> Subject: [PATCH] x86: cpu: fixup number of addressable IDs for processor
> cores in the physical package
According to the usual practice of QEMU commits, people tend to use
"i386/cpu" as the subject prefix, which indicates the code path.
> X-Mailer: git-send-email 2.24.3 (Apple Git-128)
>
> When QEMU is started with:
> -cpu host,host-cache-info=on,l3-cache=off \
Just a discussion, "l3-cache=off" doesn't work in host cache pssthu
case, do you have a specific need that you don't want to see l3 cache?
> -smp 2,sockets=1,dies=1,cores=1,threads=2
> Guest can't acquire maximum number of addressable IDs for processor cores in
> the physical package from CPUID[04H].
>
> This bug was introduced in commit d7caf13b5fcf742e5680c1d3448ba070fc811644.
> Fix it by changing the judgement condition to a >= 1.
Pls add a "Fixes" tag like:
Fixes: d7caf13b5fcf ("x86: cpu: fixup number of addressable IDs for logical
processors sharing cache")
Since this is a historical issue that deserves to be ported to the
stable branch, you can cc stable list by:
Cc: qemu-sta...@nongnu.org
> Signed-off-by: Chuang Xu <xuchuangxc...@bytedance.com>
As the patch sender, it's better to put your signature on the last line.
;-)
> Signed-off-by: Guixiong Wei <weiguixi...@bytedance.com>
> Signed-off-by: Yipeng Yin <yinyip...@bytedance.com>
> ---
> target/i386/cpu.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index cd16cb893d..0369c01153 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -6097,7 +6097,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index,
> uint32_t count,
> if (*eax & 31) {
> int host_vcpus_per_cache = 1 + ((*eax & 0x3FFC000) >> 14);
> int vcpus_per_socket = cs->nr_cores * cs->nr_threads;
> - if (cs->nr_cores > 1) {
> + if (cs->nr_cores >= 1) {
Like Igor suggested, this condition could be removed since cs->nr_cores can't
be 0.
> *eax &= ~0xFC000000;
> *eax |= (pow2ceil(cs->nr_cores) - 1) << 26;
> }
...the code is outdated, pls rebase on the latest master branch.
Regards,
Zhao
