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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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9f242dc10e
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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