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x86/vmware: Skip lapic calibration on VMware

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In a virtualized environment the APIC timer calibration can go wrong when
the host is overcommitted or the guest is running nested. This results
in the APIC timers operating at an incorrect frequency.

Since VMware supports a mechanism to retrieve the local APIC frequency we
can ask the hypervisor for it and skip the APIC calibration loop.

Signed-off-by: Renat Valiullin <rvaliullin@vmware.com>
Acked-by: Alok N Kataria <akataria@vmware.com>
Cc: virtualization@lists.linux-foundation.org
Link: http://lkml.kernel.org/r/20161004201148.GA1421@uu64vm
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Renat Valiullin 2016-10-04 13:11:48 -07:00 committed by Thomas Gleixner
parent 2df0e78b44
commit b91688f528
1 changed files with 10 additions and 2 deletions
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12
arch/x86/kernel/cpu/vmware.c
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@ -27,6 +27,7 @@
#include <asm/div64.h> #include <asm/div64.h>
#include <asm/x86_init.h> #include <asm/x86_init.h>
#include <asm/hypervisor.h> #include <asm/hypervisor.h>
#include <asm/apic.h>
#define CPUID_VMWARE_INFO_LEAF 0x40000000 #define CPUID_VMWARE_INFO_LEAF 0x40000000
#define VMWARE_HYPERVISOR_MAGIC 0x564D5868 #define VMWARE_HYPERVISOR_MAGIC 0x564D5868
@ -82,11 +83,18 @@ static void __init vmware_platform_setup(void)
VMWARE_PORT(GETHZ, eax, ebx, ecx, edx); VMWARE_PORT(GETHZ, eax, ebx, ecx, edx);
if (ebx != UINT_MAX) if (ebx != UINT_MAX) {
x86_platform.calibrate_tsc = vmware_get_tsc_khz; x86_platform.calibrate_tsc = vmware_get_tsc_khz;
else #ifdef CONFIG_X86_LOCAL_APIC
/* Skip lapic calibration since we know the bus frequency. */
lapic_timer_frequency = ecx / HZ;
pr_info("Host bus clock speed read from hypervisor : %u Hz\n",
ecx);
#endif
} else {
pr_warn("Failed to get TSC freq from the hypervisor\n"); pr_warn("Failed to get TSC freq from the hypervisor\n");
} }
}
/* /*
* While checking the dmi string information, just checking the product * While checking the dmi string information, just checking the product