Commit b91688f5 authored by Renat Valiullin's avatar Renat Valiullin Committed by Thomas Gleixner

x86/vmware: Skip lapic calibration on VMware

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: default avatarRenat Valiullin <rvaliullin@vmware.com>
Acked-by: default avatarAlok N Kataria <akataria@vmware.com>
Cc: virtualization@lists.linux-foundation.org
Link: http://lkml.kernel.org/r/20161004201148.GA1421@uu64vmSigned-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 2df0e78b
...@@ -27,6 +27,7 @@ ...@@ -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
...@@ -82,10 +83,17 @@ static void __init vmware_platform_setup(void) ...@@ -82,10 +83,17 @@ 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");
}
} }
/* /*
......
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