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Fix zen workaround on linux 6.16 #4007

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symphorien wants to merge 3 commits into from
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Fix zen workaround on linux 6.16 #4007

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aa55d6f
Update zen_workaround.c
GitMensch Aug 19, 2025
25d6b5c
Update zen_workaround.c
GitMensch Aug 19, 2025
543fc8d
zen-pmu-workaround: fix on linux 6.16
symphorien Aug 20, 2025
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19 changes: 14 additions & 5 deletions third-party/zen-pmu-workaround/zen_workaround.c
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Original file line number Diff line number Diff line change
Expand Up @@ -6,16 +6,25 @@
#include <linux/module.h>
#include <linux/tracepoint.h>
#include <linux/suspend.h>
#include <linux/version.h>
#include <asm/msr.h>

#define MODULE_NAME "zen_workaround"

#define SPECLOCKMAP_DISABLE BIT_64(54)

u64 set_speclockmap_disable(u64 msr) {
#if LINUX_VERSION_CODE < KERNEL_VERSION(6,16,0)
#define wrmsrq_safe wrmsrl_safe
#define rdmsrq_safe rdmsrl_safe
#define native_wrmsrq native_wrmsrl
#endif


static u64 set_speclockmap_disable(u64 msr) {
return msr | SPECLOCKMAP_DISABLE;
}

u64 unset_speclockmap_disable(u64 msr) {
static u64 unset_speclockmap_disable(u64 msr) {
return msr & ~SPECLOCKMAP_DISABLE;
}

Expand All @@ -26,10 +35,10 @@ static void edit_ls_cfg_on_cpu(void *info)
int cpu = get_cpu();
u64 value = 0;

if (!rdmsrl_safe(MSR_AMD64_LS_CFG, &value)) {
if (!rdmsrq_safe(MSR_AMD64_LS_CFG, &value)) {
edit_msr_func_t edit_msr = (edit_msr_func_t) info;
u64 new_value = edit_msr(value);
if (!wrmsrl_safe(MSR_AMD64_LS_CFG, new_value)) {
if (!wrmsrq_safe(MSR_AMD64_LS_CFG, new_value)) {
pr_info("MSR_AMD64_LS_CFG for cpu %d was 0x%llx, setting to 0x%llx\n",
cpu, value, new_value);
} else {
Expand All @@ -50,7 +59,7 @@ static void do_zen_workaround(edit_msr_func_t edit_msr)
void on_write_msr(void *data, unsigned int msr, u64 val, int failed)
{
if (msr == MSR_AMD64_LS_CFG && !(val & SPECLOCKMAP_DISABLE)) {
native_wrmsrl(MSR_AMD64_LS_CFG, set_speclockmap_disable(val));
native_wrmsrq(MSR_AMD64_LS_CFG, set_speclockmap_disable(val));
}
}

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