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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: Alexey Makhalov <amakhalov@vmware.com>
Acked-by: Alok 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: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Alexey Makhalov 2016-10-19 22:02:11 -07:00 committed by Thomas Gleixner
parent 1a1891d762
commit cf11372949
1 changed files with 18 additions and 19 deletions
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37
arch/x86/kernel/cpu/vmware.c
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@ -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;
uint32_t eax, ebx, ecx, edx;
VMWARE_PORT(GETHZ, eax, ebx, ecx, edx);
tsc_hz = eax | (((uint64_t)ebx) << 32);
do_div(tsc_hz, 1000);
BUG_ON(tsc_hz >> 32);
pr_info("TSC freq read from hypervisor : %lu.%03lu MHz\n",
(unsigned long) tsc_hz / 1000,
(unsigned long) tsc_hz % 1000);
if (!preset_lpj) {
lpj = ((u64)tsc_hz * 1000);
do_div(lpj, HZ);
preset_lpj = lpj;
}
return tsc_hz;
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);
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_khz / 1000,
(unsigned long) tsc_khz % 1000);
if (!preset_lpj) {
do_div(lpj, HZ);
preset_lpj = lpj;
}
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;