Commit ec8f5b46 authored by Maciej Wieczor-Retman's avatar Maciej Wieczor-Retman Committed by Ingo Molnar
Browse files

selftests/lam: Move cpu_has_la57() to use cpuinfo flag 



In current form cpu_has_la57() reports platform's support for LA57
through reading the output of cpuid. A much more useful information is
whether 5-level paging is actually enabled on the running system.

Check whether 5-level paging is enabled by trying to map a page in the
high linear address space.

Signed-off-by: default avatarMaciej Wieczor-Retman <maciej.wieczor-retman@intel.com>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/8b1ca51b13e6d94b5a42b6930d81b692cbb0bcbb.1737990375.git.maciej.wieczor-retman@intel.com
parent 7ffb7914

tools/testing/selftests/x86/lam.c

+10 −6
Original line number Diff line number Diff line
@@ -124,14 +124,18 @@ static inline int cpu_has_lam(void) 
	return (cpuinfo[0] & (1 << 26));

}



/* Check 5-level page table feature in CPUID.(EAX=07H, ECX=00H):ECX.[bit 16] */

static inline int cpu_has_la57(void)

static inline int la57_enabled(void)

{

	unsigned int cpuinfo[4];

	int ret;

	void *p;



	p = mmap((void *)HIGH_ADDR, PAGE_SIZE, PROT_READ | PROT_WRITE,

		 MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);



	__cpuid_count(0x7, 0, cpuinfo[0], cpuinfo[1], cpuinfo[2], cpuinfo[3]);

	ret = p == MAP_FAILED ? 0 : 1;



	return (cpuinfo[2] & (1 << 16));

	munmap(p, PAGE_SIZE);

	return ret;

}



/*
@@ -322,7 +326,7 @@ static int handle_mmap(struct testcases *test) 
		   flags, -1, 0);

	if (ptr == MAP_FAILED) {

		if (test->addr == HIGH_ADDR)

			if (!cpu_has_la57())

			if (!la57_enabled())

				return 3; /* unsupport LA57 */

		return 1;

	}