In-Field Scan aborts if AMX state is not in initialized state. Use
kernel_fpu_begin_mask(KFPU_AMX) to ensure AMX state is initialized.
Introduce custom FPU handling wrappers to ensure compliance with the
established FPU API semantics. This change 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@xxxxxxxxx>
Reviewed-by: Jithu Joseph <jithu.joseph@xxxxxxxxx>
Tested-by: Jithu Joseph <jithu.joseph@xxxxxxxxx>
Acked-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
V1 -> V2: Massage the changelog (Ashok), add a space to the code comment
(Ilpo), and include the header file explicitly (0-day).
---
drivers/platform/x86/intel/ifs/ifs.h | 15 +++++++++++++++
drivers/platform/x86/intel/ifs/runtest.c | 6 ++++++
2 files changed, 21 insertions(+)
diff --git a/drivers/platform/x86/intel/ifs/ifs.h b/drivers/platform/x86/intel/ifs/ifs.h
index 56b9f3e3cf76..a2ec0dab809b 100644
--- a/drivers/platform/x86/intel/ifs/ifs.h
+++ b/drivers/platform/x86/intel/ifs/ifs.h
@@ -129,6 +129,7 @@
*/
#include <linux/device.h>
#include <linux/miscdevice.h>
+#include <asm/fpu/api.h>
#define MSR_ARRAY_BIST 0x00000105
#define MSR_COPY_SCAN_HASHES 0x000002c2
@@ -325,4 +326,18 @@ 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..ca2b496a6b01 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
