在 2023/2/15 15:10, Zhao Liu 写道:
On Wed, Feb 15, 2023 at 11:28:25AM +0800, wangyanan (Y) wrote:
Date: Wed, 15 Feb 2023 11:28:25 +0800
From: "wangyanan (Y)" <wangyana...@huawei.com>
Subject: Re: [PATCH RESEND 05/18] i386/cpu: Consolidate the use of
topo_info in cpu_x86_cpuid()
在 2023/2/13 17:36, Zhao Liu 写道:
From: Zhao Liu <zhao1....@intel.com>
In cpu_x86_cpuid(), there are many variables in representing the cpu
topology, e.g., topo_info, cs->nr_cores/cs->nr_threads.
Since the names of cs->nr_cores/cs->nr_threads does not accurately
represent its meaning, the use of cs->nr_cores/cs->nr_threads is prone
to confusion and mistakes.
And the structure X86CPUTopoInfo names its memebers clearly, thus the
variable "topo_info" should be preferred.
Suggested-by: Robert Hoo <robert...@linux.intel.com>
Signed-off-by: Zhao Liu <zhao1....@intel.com>
---
target/i386/cpu.c | 30 ++++++++++++++++++------------
1 file changed, 18 insertions(+), 12 deletions(-)
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 7833505092d8..4cda84eb96f1 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -5215,11 +5215,15 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index,
uint32_t count,
uint32_t limit;
uint32_t signature[3];
X86CPUTopoInfo topo_info;
+ uint32_t cpus_per_pkg;
topo_info.dies_per_pkg = env->nr_dies;
topo_info.cores_per_die = cs->nr_cores / env->nr_dies;
topo_info.threads_per_core = cs->nr_threads;
+ cpus_per_pkg = topo_info.dies_per_pkg * topo_info.cores_per_die *
+ topo_info.threads_per_core;
+
/* Calculate & apply limits for different index ranges */
if (index >= 0xC0000000) {
limit = env->cpuid_xlevel2;
@@ -5255,8 +5259,8 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index,
uint32_t count,
*ecx |= CPUID_EXT_OSXSAVE;
}
*edx = env->features[FEAT_1_EDX];
- if (cs->nr_cores * cs->nr_threads > 1) {
- *ebx |= (cs->nr_cores * cs->nr_threads) << 16;
+ if (cpus_per_pkg > 1) {
+ *ebx |= cpus_per_pkg << 16;
*edx |= CPUID_HT;
}
if (!cpu->enable_pmu) {
@@ -5293,10 +5297,12 @@ 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) {
+ int vcpus_per_socket = cpus_per_pkg;
Would it make sense to directly use cpus_per_pkg here
+ int cores_per_socket = topo_info.cores_per_die *
+ topo_info.dies_per_pkg;
There are other places in cpu_x86_cpuid where cs->nr_cores is used
separately, why not make a global "cores_per_pkg" like cpus_per_pkg
and also tweak the other places?
Yeah, good idea.
+ if (cores_per_socket > 1) {
*eax &= ~0xFC000000;
- *eax |= (pow2ceil(cs->nr_cores) - 1) << 26;
+ *eax |= (pow2ceil(cores_per_socket) - 1) << 26;
}
if (host_vcpus_per_cache > vcpus_per_socket) {
*eax &= ~0x3FFC000;
@@ -5436,12 +5442,12 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index,
uint32_t count,
switch (count) {
case 0:
*eax = apicid_core_offset(&topo_info);
- *ebx = cs->nr_threads;
+ *ebx = topo_info.threads_per_core;
There are many other places in cpu_x86_cpuid where cs->nr_threads
is used separately, such as encode_cache_cpuid4(***), should we
replace them all?
In a previous patch [1], I replaced the use of cs->nr_threads/nr_cores in
the call of encode_cache_cpuid4().
The cleanest way is to pass topo_info to encode_cache_cpuid4(), but this
involves the modification of the interface format and the use of the
cache topo level, so I included it in a follow-up patch [2].
Ok, I see. I have not reached there.😉
[1]: [PATCH RESEND 04/18] i386/cpu: Fix number of addressable IDs in
CPUID.04,
https://lists.gnu.org/archive/html/qemu-devel/2023-02/msg03188.html
[2]: [PATCH RESEND 15/18] i386: Use CPUCacheInfo.share_level to encode
CPUID[4].EAX[bits 25:14],
https://lists.gnu.org/archive/html/qemu-devel/2023-02/msg03199.html
*ecx |= CPUID_TOPOLOGY_LEVEL_SMT;
break;
case 1:
*eax = apicid_pkg_offset(&topo_info);
- *ebx = cs->nr_cores * cs->nr_threads;
+ *ebx = cpus_per_pkg;
*ecx |= CPUID_TOPOLOGY_LEVEL_CORE;
break;
default:
@@ -5472,7 +5478,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index,
uint32_t count,
switch (count) {
case 0:
*eax = apicid_core_offset(&topo_info);
- *ebx = cs->nr_threads;
+ *ebx = topo_info.threads_per_core;
*ecx |= CPUID_TOPOLOGY_LEVEL_SMT;
break;
case 1:
@@ -5482,7 +5488,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index,
uint32_t count,
break;
case 2:
*eax = apicid_pkg_offset(&topo_info);
- *ebx = cs->nr_cores * cs->nr_threads;
+ *ebx = cpus_per_pkg;
*ecx |= CPUID_TOPOLOGY_LEVEL_DIE;
break;
default:
@@ -5707,7 +5713,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index,
uint32_t count,
* discards multiple thread information if it is set.
* So don't set it here for Intel to make Linux guests happy.
*/
- if (cs->nr_cores * cs->nr_threads > 1) {
+ if (cpus_per_pkg > 1) {
if (env->cpuid_vendor1 != CPUID_VENDOR_INTEL_1 ||
env->cpuid_vendor2 != CPUID_VENDOR_INTEL_2 ||
env->cpuid_vendor3 != CPUID_VENDOR_INTEL_3) {
@@ -5769,7 +5775,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index,
uint32_t count,
*eax |= (cpu_x86_virtual_addr_width(env) << 8);
}
*ebx = env->features[FEAT_8000_0008_EBX];
- if (cs->nr_cores * cs->nr_threads > 1) {
+ if (cpus_per_pkg > 1) {
/*
* Bits 15:12 is "The number of bits in the initial
* Core::X86::Apic::ApicId[ApicId] value that indicate
@@ -5777,7 +5783,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index,
uint32_t count,
* Bits 7:0 is "The number of threads in the package is NC+1"
*/
*ecx = (apicid_pkg_offset(&topo_info) << 12) |
- ((cs->nr_cores * cs->nr_threads) - 1);
+ (cpus_per_pkg - 1);
} else {
*ecx = 0;
}
Thanks,
Yanan
