After tilerelease instruction, AMX tiles are in INIT state. According to
Intel SDM vol 1. 13.10: "If RFBM[i] = 1, XSTATE_BV[i] is set to the
value of XINUSE[i].", XSTATE_BV[18] should be cleared after xsavec.
On the other hand, according to Intel SDM vol 1. 13.4.3: "If XCOMP_BV[i] =
1, state component i is located at a byte offset locationI from the base
address of the XSAVE area". Since at the time of xsavec, XCR0[18] is set
indicating AMX tile data component is still enabled, xcomp_bv[18] should be
set.
Complete the checks by adding the assert to xcomp_bv[18] after xsavec.
Signed-off-by: Mingwei Zhang <mizhang@xxxxxxxxxx>
---
tools/testing/selftests/kvm/x86_64/amx_test.c | 30 +++++++++++++++++--
1 file changed, 27 insertions(+), 3 deletions(-)
diff --git a/tools/testing/selftests/kvm/x86_64/amx_test.c b/tools/testing/selftests/kvm/x86_64/amx_test.c
index b2369f956fea..18203e399e9d 100644
--- a/tools/testing/selftests/kvm/x86_64/amx_test.c
+++ b/tools/testing/selftests/kvm/x86_64/amx_test.c
@@ -41,6 +41,12 @@
#define XSAVE_HDR_OFFSET 512
+struct xstate_header {
+ u64 xfeatures;
+ u64 xcomp_bv;
+ u64 reserved[6];
+} __packed;
+
struct xsave_data {
u8 area[XSAVE_SIZE];
} __aligned(64);
@@ -160,12 +166,26 @@ static void set_tilecfg(struct tile_config *cfg)
static void set_xstatebv(void *data, uint64_t bv)
{
- *(uint64_t *)(data + XSAVE_HDR_OFFSET) = bv;
+ struct xstate_header *header =
+ (struct xstate_header *)(data + XSAVE_HDR_OFFSET);
+
+ header->xfeatures = bv;
}
static u64 get_xstatebv(void *data)
{
- return *(u64 *)(data + XSAVE_HDR_OFFSET);
+ struct xstate_header *header =
+ (struct xstate_header *)(data + XSAVE_HDR_OFFSET);
+
+ return header->xfeatures;
+}
+
+static u64 get_xcompbv(void *data)
+{
+ struct xstate_header *header =
+ (struct xstate_header *)(data + XSAVE_HDR_OFFSET);
+
+ return header->xcomp_bv;
}
static void init_regs(void)
@@ -204,10 +224,14 @@ static void __attribute__((__flatten__)) guest_code(struct tile_config *amx_cfg,
GUEST_SYNC(4);
__tilerelease();
GUEST_SYNC(5);
- /* bit 18 not in the XSTATE_BV after xsavec() */
+ /*
+ * After xsavec() bit 18 is cleared in the XSTATE_BV but is set in
+ * the XCOMP_BV.
+ */
set_xstatebv(xsave_data, XFEATURE_MASK_XTILEDATA);
__xsavec(xsave_data, XFEATURE_MASK_XTILEDATA);
GUEST_ASSERT((get_xstatebv(xsave_data) & XFEATURE_MASK_XTILEDATA) == 0);
+ GUEST_ASSERT((get_xcompbv(xsave_data) & XFEATURE_MASK_XTILEDATA) == XFEATURE_MASK_XTILEDATA);
/* xfd=0x40000, disable amx tiledata */
wrmsr(MSR_IA32_XFD, XFEATURE_MASK_XTILEDATA);
--
2.39.0.314.g84b9a713c41-goog
