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When running on VMware's platform, we have seen situations where the AP's try to calibrate the lpj values and fail to get good calibration runs becasue of timing issues. As a result delays don't work correctly on all cpus. The solutions is to set preset_lpj value based on the current tsc frequency value. This is similar to what KVM does as well. Signed-off-by: Alok N Kataria <akataria@vmware.com> LKML-Reference: <1280790637.14933.29.camel@ank32.eng.vmware.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
135 lines
4.1 KiB
C
135 lines
4.1 KiB
C
/*
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* VMware Detection code.
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*
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* Copyright (C) 2008, VMware, Inc.
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* Author : Alok N Kataria <akataria@vmware.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
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* NON INFRINGEMENT. See the GNU General Public License for more
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* details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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*/
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#include <linux/dmi.h>
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#include <linux/module.h>
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#include <asm/div64.h>
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#include <asm/x86_init.h>
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#include <asm/hypervisor.h>
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#define CPUID_VMWARE_INFO_LEAF 0x40000000
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#define VMWARE_HYPERVISOR_MAGIC 0x564D5868
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#define VMWARE_HYPERVISOR_PORT 0x5658
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#define VMWARE_PORT_CMD_GETVERSION 10
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#define VMWARE_PORT_CMD_GETHZ 45
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#define VMWARE_PORT(cmd, eax, ebx, ecx, edx) \
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__asm__("inl (%%dx)" : \
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"=a"(eax), "=c"(ecx), "=d"(edx), "=b"(ebx) : \
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"0"(VMWARE_HYPERVISOR_MAGIC), \
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"1"(VMWARE_PORT_CMD_##cmd), \
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"2"(VMWARE_HYPERVISOR_PORT), "3"(UINT_MAX) : \
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"memory");
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static inline int __vmware_platform(void)
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{
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uint32_t eax, ebx, ecx, edx;
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VMWARE_PORT(GETVERSION, eax, ebx, ecx, edx);
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return eax != (uint32_t)-1 && ebx == VMWARE_HYPERVISOR_MAGIC;
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}
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static unsigned long vmware_get_tsc_khz(void)
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{
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uint64_t tsc_hz, lpj;
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uint32_t eax, ebx, ecx, edx;
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VMWARE_PORT(GETHZ, eax, ebx, ecx, edx);
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tsc_hz = eax | (((uint64_t)ebx) << 32);
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do_div(tsc_hz, 1000);
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BUG_ON(tsc_hz >> 32);
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printk(KERN_INFO "TSC freq read from hypervisor : %lu.%03lu MHz\n",
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(unsigned long) tsc_hz / 1000,
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(unsigned long) tsc_hz % 1000);
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if (!preset_lpj) {
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lpj = ((u64)tsc_hz * 1000);
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do_div(lpj, HZ);
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preset_lpj = lpj;
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}
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return tsc_hz;
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}
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static void __init vmware_platform_setup(void)
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{
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uint32_t eax, ebx, ecx, edx;
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VMWARE_PORT(GETHZ, eax, ebx, ecx, edx);
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if (ebx != UINT_MAX)
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x86_platform.calibrate_tsc = vmware_get_tsc_khz;
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else
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printk(KERN_WARNING
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"Failed to get TSC freq from the hypervisor\n");
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}
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/*
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* While checking the dmi string infomation, just checking the product
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* serial key should be enough, as this will always have a VMware
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* specific string when running under VMware hypervisor.
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*/
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static bool __init vmware_platform(void)
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{
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if (cpu_has_hypervisor) {
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unsigned int eax;
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unsigned int hyper_vendor_id[3];
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cpuid(CPUID_VMWARE_INFO_LEAF, &eax, &hyper_vendor_id[0],
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&hyper_vendor_id[1], &hyper_vendor_id[2]);
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if (!memcmp(hyper_vendor_id, "VMwareVMware", 12))
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return true;
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} else if (dmi_available && dmi_name_in_serial("VMware") &&
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__vmware_platform())
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return true;
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return false;
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}
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/*
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* VMware hypervisor takes care of exporting a reliable TSC to the guest.
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* Still, due to timing difference when running on virtual cpus, the TSC can
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* be marked as unstable in some cases. For example, the TSC sync check at
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* bootup can fail due to a marginal offset between vcpus' TSCs (though the
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* TSCs do not drift from each other). Also, the ACPI PM timer clocksource
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* is not suitable as a watchdog when running on a hypervisor because the
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* kernel may miss a wrap of the counter if the vcpu is descheduled for a
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* long time. To skip these checks at runtime we set these capability bits,
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* so that the kernel could just trust the hypervisor with providing a
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* reliable virtual TSC that is suitable for timekeeping.
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*/
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static void __cpuinit vmware_set_cpu_features(struct cpuinfo_x86 *c)
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{
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set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC);
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set_cpu_cap(c, X86_FEATURE_TSC_RELIABLE);
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}
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const __refconst struct hypervisor_x86 x86_hyper_vmware = {
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.name = "VMware",
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.detect = vmware_platform,
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.set_cpu_features = vmware_set_cpu_features,
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.init_platform = vmware_platform_setup,
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};
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EXPORT_SYMBOL(x86_hyper_vmware);
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