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Commit cf113729 authored by Alexey Makhalov's avatar Alexey Makhalov Committed by Thomas Gleixner
Browse files

x86/vmware: Read tsc_khz only once at boot time 



Re-factor the vmware platform setup code to query the hypervisor for tsc
frequency only once during boot. Since the VMware hypervisor guarantees
constant TSC, calibrate_tsc now uses the saved value.

Signed-off-by: default avatarAlexey Makhalov <amakhalov@vmware.com>
Acked-by: default avatarAlok N Kataria <akataria@vmware.com>
Cc: virtualization@lists.linux-foundation.org
Link: http://lkml.kernel.org/r/20161020050211.GA25304@amakhalov-virtual-machine


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 1a1891d7

arch/x86/kernel/cpu/vmware.c

+18 −19
Original line number Diff line number Diff line
@@ -47,6 +47,8 @@ 
			"2"(VMWARE_HYPERVISOR_PORT), "3"(UINT_MAX) :	\

			"memory");



static unsigned long vmware_tsc_khz __ro_after_init;



static inline int __vmware_platform(void)

{

	uint32_t eax, ebx, ecx, edx;
@@ -56,35 +58,32 @@ static inline int __vmware_platform(void) 


static unsigned long vmware_get_tsc_khz(void)

{

	uint64_t tsc_hz, lpj;

	return vmware_tsc_khz;

}



static void __init vmware_platform_setup(void)

{

	uint32_t eax, ebx, ecx, edx;

	uint64_t lpj, tsc_khz;



	VMWARE_PORT(GETHZ, eax, ebx, ecx, edx);



	tsc_hz = eax | (((uint64_t)ebx) << 32);

	do_div(tsc_hz, 1000);

	BUG_ON(tsc_hz >> 32);

	if (ebx != UINT_MAX) {

		lpj = tsc_khz = eax | (((uint64_t)ebx) << 32);

		do_div(tsc_khz, 1000);

		WARN_ON(tsc_khz >> 32);

		pr_info("TSC freq read from hypervisor : %lu.%03lu MHz\n",

			 (unsigned long) tsc_hz / 1000,

			 (unsigned long) tsc_hz % 1000);

			(unsigned long) tsc_khz / 1000,

			(unsigned long) tsc_khz % 1000);



		if (!preset_lpj) {

		lpj = ((u64)tsc_hz * 1000);

			do_div(lpj, HZ);

			preset_lpj = lpj;

		}



	return tsc_hz;

}



static void __init vmware_platform_setup(void)

{

	uint32_t eax, ebx, ecx, edx;



	VMWARE_PORT(GETHZ, eax, ebx, ecx, edx);



	if (ebx != UINT_MAX) {

		vmware_tsc_khz = tsc_khz;

		x86_platform.calibrate_tsc = vmware_get_tsc_khz;



#ifdef CONFIG_X86_LOCAL_APIC

		/* Skip lapic calibration since we know the bus frequency. */

		lapic_timer_frequency = ecx / HZ;