Messages in this thread Patch in this message | | | From | "Chang S. Bae" <> | Subject | [PATCH 2/2] platform/x86/intel/ifs: Initialize AMX state for the scan test | Date | Tue, 30 Apr 2024 14:25:08 -0700 |
| |
The scan test does not start when the AMX state remains active and is not re-initialized. With the extension of kernel_fpu_begin_mask(), the driver code can now initialize the state properly.
Introduce custom FPU handling wrappers to ensure compliant with the established FPU API semantics, as kernel_fpu_begin() exclusively sets legacy states. This follows the EFI case from commit b0dc553cfc9d ("x86/fpu: Make the EFI FPU calling convention explicit").
Then, use these wrappers to surround the MSR_ACTIVATE_SCAN write to minimize the critical section. To prevent unnecessary delays, invoke ifs_fpu_begin() before entering the rendezvous loop.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com> Reviewed-by: Jithu Joseph <jithu.joseph@intel.com> Tested-by: Jithu Joseph <jithu.joseph@intel.com> --- drivers/platform/x86/intel/ifs/ifs.h | 14 ++++++++++++++ drivers/platform/x86/intel/ifs/runtest.c | 6 ++++++ 2 files changed, 20 insertions(+)
diff --git a/drivers/platform/x86/intel/ifs/ifs.h b/drivers/platform/x86/intel/ifs/ifs.h index 56b9f3e3cf76..71d8b50854b2 100644 --- a/drivers/platform/x86/intel/ifs/ifs.h +++ b/drivers/platform/x86/intel/ifs/ifs.h @@ -325,4 +325,18 @@ int do_core_test(int cpu, struct device *dev); extern struct attribute *plat_ifs_attrs[]; extern struct attribute *plat_ifs_array_attrs[]; +static inline void ifs_fpu_begin(void) +{ + /* + * The AMX state must be initialized prior to executing In-Field + * Scan tests, according to Intel SDM. + */ + kernel_fpu_begin_mask(KFPU_AMX); +} + +static inline void ifs_fpu_end(void) +{ + kernel_fpu_end(); +} + #endif diff --git a/drivers/platform/x86/intel/ifs/runtest.c b/drivers/platform/x86/intel/ifs/runtest.c index 95b4b71fab53..a35eac7c0b44 100644 --- a/drivers/platform/x86/intel/ifs/runtest.c +++ b/drivers/platform/x86/intel/ifs/runtest.c @@ -188,6 +188,9 @@ static int doscan(void *data) /* Only the first logical CPU on a core reports result */ first = cpumask_first(cpu_smt_mask(cpu)); + /* Prepare FPU state before entering the rendezvous loop*/ + ifs_fpu_begin(); + wait_for_sibling_cpu(&scan_cpus_in, NSEC_PER_SEC); /* @@ -199,6 +202,9 @@ static int doscan(void *data) * are processed in a single pass) before it retires. */ wrmsrl(MSR_ACTIVATE_SCAN, params->activate->data); + + ifs_fpu_end(); + rdmsrl(MSR_SCAN_STATUS, status.data); trace_ifs_status(ifsd->cur_batch, start, stop, status.data); -- 2.34.1
| |