[PATCH 3/3] selftest: Support amx selftest

Yang Zhong
2021-12-21T14:20:17Z

This selftest do two test cases, one is to trigger #NM
exception and check MSR XFD_ERR value. Another case is
guest load tile data into tmm0 registers and trap to host
side to check memory data after save/restore.

Signed-off-by: Yang Zhong <yang.zhong@intel.com>
---
tools/testing/selftests/kvm/Makefile | 1 +
tools/testing/selftests/kvm/x86_64/amx_test.c | 370 ++++++++++++++++++
2 files changed, 371 insertions(+)
create mode 100644 tools/testing/selftests/kvm/x86_64/amx_test.c

diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index c4e34717826a..ecb1fe022111 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -75,6 +75,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/xen_shinfo_test
TEST_GEN_PROGS_x86_64 += x86_64/xen_vmcall_test
TEST_GEN_PROGS_x86_64 += x86_64/vmx_pi_mmio_test
TEST_GEN_PROGS_x86_64 += x86_64/sev_migrate_tests
+TEST_GEN_PROGS_x86_64 += x86_64/amx_test
TEST_GEN_PROGS_x86_64 += demand_paging_test
TEST_GEN_PROGS_x86_64 += dirty_log_test
TEST_GEN_PROGS_x86_64 += dirty_log_perf_test
diff --git a/tools/testing/selftests/kvm/x86_64/amx_test.c b/tools/testing/selftests/kvm/x86_64/amx_test.c
new file mode 100644
index 000000000000..76ae44622923
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/amx_test.c
@@ -0,0 +1,370 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * amx tests
+ *
+ * Copyright (C) 2021, Intel, Inc.
+ *
+ * Tests for amx #NM exception and save/restore.
+ */
+
+#define _GNU_SOURCE /* for program_invocation_short_name */
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/syscall.h>
+
+#include "test_util.h"
+
+#include "kvm_util.h"
+#include "processor.h"
+#include "vmx.h"
+
+#ifndef __x86_64__
+# error This test is 64-bit only
+#endif
+
+#define VCPU_ID 0
+#define X86_FEATURE_XSAVE (1 << 26)
+#define X86_FEATURE_OSXSAVE (1 << 27)
+
+#define PAGE_SIZE (1 << 12)
+#define NUM_TILES 8
+#define TILE_SIZE 1024
+#define XSAVE_SIZE ((NUM_TILES * TILE_SIZE) + PAGE_SIZE)
+
+/* Tile configuration associated: */
+#define MAX_TILES 16
+#define RESERVED_BYTES 14
+
+#define XFEATURE_XTILECFG 17
+#define XFEATURE_XTILEDATA 18
+#define XFEATURE_MASK_XTILECFG (1 << XFEATURE_XTILECFG)
+#define XFEATURE_MASK_XTILEDATA (1 << XFEATURE_XTILEDATA)
+#define XFEATURE_MASK_XTILE (XFEATURE_MASK_XTILECFG | XFEATURE_MASK_XTILEDATA)
+
+#define TILE_CPUID 0x1d
+#define XSTATE_CPUID 0xd
+#define TILE_PALETTE_CPUID_SUBLEAVE 0x1
+#define XSTATE_USER_STATE_SUBLEAVE 0x0
+
+struct tile_config {
+ u8 palette_id;
+ u8 start_row;
+ u8 reserved[RESERVED_BYTES];
+ u16 colsb[MAX_TILES];
+ u8 rows[MAX_TILES];
+};
+
+struct tile_data {
+ u8 data[NUM_TILES * TILE_SIZE];
+};
+
+struct xtile_info {
+ u16 bytes_per_tile;
+ u16 bytes_per_row;
+ u16 max_names;
+ u16 max_rows;
+ u32 xsave_offset;
+ u32 xsave_size;
+};
+
+static struct xtile_info xtile;
+
+static inline u64 __xgetbv(u32 index)
+{
+ u32 eax, edx;
+
+ asm volatile("xgetbv;"
+ : "=a" (eax), "=d" (edx)
+ : "c" (index));
+ return eax + ((u64)edx << 32);
+}
+
+static inline void __xsetbv(u32 index, u64 value)
+{
+ u32 eax = value;
+ u32 edx = value >> 32;
+
+ asm volatile("xsetbv" :: "a" (eax), "d" (edx), "c" (index));
+}
+
+static inline void __ldtilecfg(void *cfg)
+{
+ asm volatile(".byte 0xc4,0xe2,0x78,0x49,0x00"
+ : : "a"(cfg));
+}
+
+static inline void __tileloadd(void *tile)
+{
+ asm volatile(".byte 0xc4,0xe2,0x7b,0x4b,0x04,0x10"
+ : : "a"(tile), "d"(0));
+}
+
+static inline void __tilerelease(void)
+{
+ asm volatile(".byte 0xc4, 0xe2, 0x78, 0x49, 0xc0" ::);
+}
+
+static inline void check_cpuid_xsave(void)
+{
+ uint32_t eax, ebx, ecx, edx;
+
+ eax = 1;
+ ecx = 0;
+ cpuid(&eax, &ebx, &ecx, &edx);
+ if (!(ecx & X86_FEATURE_XSAVE))
+ GUEST_ASSERT(!"cpuid: no CPU xsave support!");
+ if (!(ecx & X86_FEATURE_OSXSAVE))
+ GUEST_ASSERT(!"cpuid: no OS xsave support!");
+}
+
+static bool check_xsave_supports_xtile(void)
+{
+ return __xgetbv(0) & XFEATURE_MASK_XTILE;
+}
+
+static bool enum_xtile_config(void)
+{
+ u32 eax, ebx, ecx, edx;
+
+ eax = TILE_CPUID;
+ ecx = TILE_PALETTE_CPUID_SUBLEAVE;
+
+ cpuid(&eax, &ebx, &ecx, &edx);
+ if (!eax || !ebx || !ecx)
+ return false;
+
+ xtile.max_names = ebx >> 16;
+ if (xtile.max_names < NUM_TILES)
+ return false;
+
+ xtile.bytes_per_tile = eax >> 16;
+ if (xtile.bytes_per_tile < TILE_SIZE)
+ return false;
+
+ xtile.bytes_per_row = ebx;
+ xtile.max_rows = ecx;
+
+ return true;
+}
+
+static bool enum_xsave_tile(void)
+{
+ u32 eax, ebx, ecx, edx;
+
+ eax = XSTATE_CPUID;
+ ecx = XFEATURE_XTILEDATA;
+
+ cpuid(&eax, &ebx, &ecx, &edx);
+ if (!eax || !ebx)
+ return false;
+
+ xtile.xsave_offset = ebx;
+ xtile.xsave_size = eax;
+
+ return true;
+}
+
+static bool check_xsave_size(void)
+{
+ u32 eax, ebx, ecx, edx;
+ bool valid = false;
+
+ eax = XSTATE_CPUID;
+ ecx = XSTATE_USER_STATE_SUBLEAVE;
+
+ cpuid(&eax, &ebx, &ecx, &edx);
+ if (ebx && ebx <= XSAVE_SIZE)
+ valid = true;
+
+ return valid;
+}
+
+static bool check_xtile_info(void)
+{
+ bool ret = false;
+
+ if (!check_xsave_size())
+ return ret;
+
+ if (!enum_xsave_tile())
+ return ret;
+
+ if (!enum_xtile_config())
+ return ret;
+
+ if (sizeof(struct tile_data) >= xtile.xsave_size)
+ ret = true;
+
+ return ret;
+}
+
+static void set_tilecfg(struct tile_config *cfg)
+{
+ int i;
+
+ /* Only palette id 1 */
+ cfg->palette_id = 1;
+ for (i = 0; i < xtile.max_names; i++) {
+ cfg->colsb[i] = xtile.bytes_per_row;
+ cfg->rows[i] = xtile.max_rows;
+ }
+}
+
+static void init_regs(void)
+{
+ uint64_t cr4, xcr0;
+
+ /* turn on CR4.OSXSAVE */
+ cr4 = get_cr4();
+ cr4 |= X86_CR4_OSXSAVE;
+ set_cr4(cr4);
+
+ xcr0 = __xgetbv(0);
+ xcr0 |= XFEATURE_MASK_XTILE;
+ __xsetbv(0x0, xcr0);
+}
+
+static void __attribute__((__flatten__)) guest_code(struct tile_config *amx_cfg,
+ struct tile_data *tiledata)
+{
+ init_regs();
+ check_cpuid_xsave();
+ GUEST_ASSERT(check_xsave_supports_xtile());
+ GUEST_ASSERT(check_xtile_info());
+
+ /* check xtile configs */
+ GUEST_ASSERT(xtile.xsave_offset == 2816);
+ GUEST_ASSERT(xtile.xsave_size == 8192);
+ GUEST_ASSERT(xtile.max_names == 8);
+ GUEST_ASSERT(xtile.bytes_per_tile == 1024);
+ GUEST_ASSERT(xtile.bytes_per_row == 64);
+ GUEST_ASSERT(xtile.max_rows == 16);
+
+ /* xfd=0, enable amx */
+ wrmsr(MSR_IA32_XFD, 0);
+ GUEST_ASSERT(rdmsr(MSR_IA32_XFD) == 0);
+ set_tilecfg(amx_cfg);
+ __ldtilecfg(amx_cfg);
+ /* Check save/restore when trap to userspace */
+ __tileloadd(tiledata);
+ GUEST_SYNC(1);
+
+ /* xfd=0x40000, disable amx tiledata */
+ wrmsr(MSR_IA32_XFD, XFEATURE_MASK_XTILEDATA);
+ GUEST_ASSERT(rdmsr(MSR_IA32_XFD) == XFEATURE_MASK_XTILEDATA);
+ set_tilecfg(amx_cfg);
+ __ldtilecfg(amx_cfg);
+ /* Trigger #NM exception */
+ __tileloadd(tiledata);
+
+ GUEST_DONE();
+}
+
+void guest_nm_handler(struct ex_regs *regs)
+{
+ /* Check if #NM is triggered by XFEATURE_MASK_XTILEDATA */
+ GUEST_ASSERT(rdmsr(MSR_IA32_XFD_ERR) == XFEATURE_MASK_XTILEDATA);
+ /* Clear xfd_err */
+ wrmsr(MSR_IA32_XFD_ERR, 0);
+ GUEST_SYNC(2);
+}
+
+int main(int argc, char *argv[])
+{
+ struct kvm_cpuid_entry2 *entry;
+ struct kvm_regs regs1;
+ bool amx_supported = false;
+ struct kvm_vm *vm;
+ struct kvm_run *run;
+ struct kvm_x86_state *state;
+ int xsave_restore_size = 0;
+ vm_vaddr_t amx_cfg, tiledata;
+ struct ucall uc;
+ u32 amx_offset;
+ int stage, ret;
+
+ /* Create VM */
+ vm = vm_create_default(VCPU_ID, 0, guest_code);
+
+ entry = kvm_get_supported_cpuid_entry(1);
+ if (!(entry->ecx & X86_FEATURE_XSAVE)) {
+ print_skip("XSAVE feature not supported");
+ return 0;
+ }
+
+ if (kvm_get_cpuid_max_basic() >= 0xd) {
+ entry = kvm_get_supported_cpuid_index(0xd, 0);
+ amx_supported = entry && !!(entry->eax & XFEATURE_MASK_XTILE);
+ if (!amx_supported) {
+ print_skip("AMX is not supported by the vCPU and eax=0x%x", entry->eax);
+ return 0;
+ }
+ /* Get xsave/restore max size */
+ xsave_restore_size = entry->ecx;
+ }
+
+ run = vcpu_state(vm, VCPU_ID);
+ vcpu_regs_get(vm, VCPU_ID, &regs1);
+
+ /* Register #NM handler */
+ vm_init_descriptor_tables(vm);
+ vcpu_init_descriptor_tables(vm, VCPU_ID);
+ vm_install_exception_handler(vm, NM_VECTOR, guest_nm_handler);
+
+ /* amx cfg for guest_code */
+ amx_cfg = vm_vaddr_alloc_page(vm);
+ memset(addr_gva2hva(vm, amx_cfg), 0x0, getpagesize());
+
+ /* amx tiledatas for guest_code */
+ tiledata = vm_vaddr_alloc_pages(vm, 2);
+ memset(addr_gva2hva(vm, tiledata), rand() | 1, 2 * getpagesize());
+ vcpu_args_set(vm, VCPU_ID, 2, amx_cfg, tiledata);
+
+ for (stage = 1; ; stage++) {
+ _vcpu_run(vm, VCPU_ID);
+ TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
+ "Stage %d: unexpected exit reason: %u (%s),\n",
+ stage, run->exit_reason,
+ exit_reason_str(run->exit_reason));
+
+ switch (get_ucall(vm, VCPU_ID, &uc)) {
+ case UCALL_ABORT:
+ TEST_FAIL("%s at %s:%ld", (const char *)uc.args[0],
+ __FILE__, uc.args[1]);
+ /* NOT REACHED */
+ case UCALL_SYNC:
+ switch (uc.args[1]) {
+ case 1:
+ fprintf(stderr,
+ "Exit VM by GUEST_SYNC(1), check save/restore.\n");
+
+ /* Compacted mode, get amx offset by xsave area
+ * size subtract 8K amx size.
+ */
+ amx_offset = xsave_restore_size - NUM_TILES*TILE_SIZE;
+ state = vcpu_save_state(vm, VCPU_ID);
+ void *amx_start = (void *)state->xsave + amx_offset;
+ void *tiles_data = (void *)addr_gva2hva(vm, tiledata);
+ /* Only check TMM0 register, 1 tile */
+ ret = memcmp(amx_start, tiles_data, TILE_SIZE);
+ TEST_ASSERT(ret == 0, "memcmp failed, ret=%d\n", ret);
+ kvm_x86_state_cleanup(state);
+ break;
+ case 2:
+ fprintf(stderr,
+ "Exit VM by GUEST_SYNC(2), generate #NM exception.\n");
+ goto done;
+ }
+ break;
+ case UCALL_DONE:
+ goto done;
+ default:
+ TEST_FAIL("Unknown ucall %lu", uc.cmd);
+ }
+ }
+done:
+ kvm_vm_free(vm);
+}