x86/vmware: Skip lapic calibration on VMware (b91688f5) · Commits · 戴 / test

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>

arch/x86/kernel/cpu/vmware.c

+10 −2

Original line number	Diff line number	Diff line
		@@ -27,6 +27,7 @@
		#include <asm/div64.h>
		#include <asm/x86_init.h>
		#include <asm/hypervisor.h>
		#include <asm/apic.h>

		#define CPUID_VMWARE_INFO_LEAF 0x40000000
		#define VMWARE_HYPERVISOR_MAGIC 0x564D5868
		@@ -82,11 +83,18 @@ static void __init vmware_platform_setup(void)

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

		if (ebx != UINT_MAX)
		if (ebx != UINT_MAX) {
		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");
		}
		}

		/*
		* While checking the dmi string information, just checking the product

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