linux/arch/x86/kernel/cpu
Thomas Gleixner c65732e4f7 x86/cpu: Restore CPUID_8000_0008_EBX reload
The recent commt which addresses the x86_phys_bits corruption with
encrypted memory on CPUID reload after a microcode update lost the reload
of CPUID_8000_0008_EBX as well.

As a consequence IBRS and IBRS_FW are not longer detected

Restore the behaviour by bringing the reload of CPUID_8000_0008_EBX
back. This restore has a twist due to the convoluted way the cpuid analysis
works:

CPUID_8000_0008_EBX is used by AMD to enumerate IBRB, IBRS, STIBP. On Intel
EBX is not used. But the speculation control code sets the AMD bits when
running on Intel depending on the Intel specific speculation control
bits. This was done to use the same bits for alternatives.

The change which moved the 8000_0008 evaluation out of get_cpu_cap() broke
this nasty scheme due to ordering. So that on Intel the store to
CPUID_8000_0008_EBX clears the IBRB, IBRS, STIBP bits which had been set
before by software.

So the actual CPUID_8000_0008_EBX needs to go back to the place where it
was and the phys/virt address space calculation cannot touch it.

In hindsight this should have used completely synthetic bits for IBRB,
IBRS, STIBP instead of reusing the AMD bits, but that's for 4.18.

/me needs to find time to cleanup that steaming pile of ...

Fixes: d94a155c59 ("x86/cpu: Prevent cpuinfo_x86::x86_phys_bits adjustment corruption")
Reported-by: Jörg Otte <jrg.otte@gmail.com>
Reported-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Jörg Otte <jrg.otte@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: kirill.shutemov@linux.intel.com
Cc: Borislav Petkov <bp@alien8.de
Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1805021043510.1668@nanos.tec.linutronix.de
2018-05-02 16:44:38 +02:00
..
mcheck Merge branch 'x86-timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-04-02 16:18:31 -07:00
microcode x86/microcode: Do not exit early from __reload_late() 2018-04-24 09:48:22 +02:00
mtrr x86/cpu: Rename cpu_data.x86_mask to cpu_data.x86_stepping 2018-02-15 01:15:52 +01:00
.gitignore
Makefile x86/pconfig: Detect PCONFIG targets 2018-03-12 12:10:54 +01:00
amd.c x86/jailhouse: Allow to use PCI_MMCONFIG without ACPI 2018-03-08 12:30:39 +01:00
aperfmperf.c
bugs.c x86/speculation: Use IBRS if available before calling into firmware 2018-02-20 09:38:33 +01:00
centaur.c Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-02-14 17:02:15 -08:00
common.c x86/cpu: Restore CPUID_8000_0008_EBX reload 2018-05-02 16:44:38 +02:00
cpu.h
cpuid-deps.c x86/cpuid: Switch to 'static const' specifier 2018-03-08 12:23:42 +01:00
cyrix.c x86/cpu: Rename cpu_data.x86_mask to cpu_data.x86_stepping 2018-02-15 01:15:52 +01:00
hypervisor.c
intel.c x86/cpu/intel: Add missing TLB cpuid values 2018-04-26 21:42:44 +02:00
intel_cacheinfo.c
intel_pconfig.c x86/pconfig: Detect PCONFIG targets 2018-03-12 12:10:54 +01:00
intel_rdt.c Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-02-14 17:02:15 -08:00
intel_rdt.h
intel_rdt_ctrlmondata.c
intel_rdt_monitor.c
intel_rdt_rdtgroup.c x86/intel_rdt: Fix incorrect returned value when creating rdgroup sub-directory in resctrl file system 2018-02-23 08:03:21 +01:00
match.c
mkcapflags.sh
mshyperv.c ARM: 2018-04-09 11:42:31 -07:00
perfctr-watchdog.c
powerflags.c
proc.c x86/cpu: Change type of x86_cache_size variable to unsigned int 2018-02-15 01:15:53 +01:00
rdrand.c
scattered.c Merge branch 'x86/hyperv' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-02-01 15:04:17 +01:00
topology.c
transmeta.c
umc.c
vmware.c