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x86/microcode/intel: Replace sync_core() with native_cpuid() 

The Intel microcode driver is using sync_core() to mean "do CPUID
with EAX=1".  I want to rework sync_core(), but first the Intel
microcode driver needs to stop depending on its current behavior.

Reported-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Juergen Gross <jgross@suse.com>
Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Matthew Whitehead <tedheadster@gmail.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: xen-devel <Xen-devel@lists.xen.org>
Link: http://lkml.kernel.org/r/535a025bb91fed1a019c5412b036337ad239e5bb.1481307769.git.luto@kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Andy Lutomirski 2016-12-09 10:24:07 -08:00 committed by Thomas Gleixner
parent 426d1aff31
commit 484d0e5c79
1 changed files with 23 additions and 3 deletions
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26
arch/x86/kernel/cpu/microcode/intel.c
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@ -368,6 +368,26 @@ scan_microcode(void *data, size_t size, struct ucode_cpu_info *uci, bool save)
return patch;
}
static void cpuid_1(void)
{
/*
* According to the Intel SDM, Volume 3, 9.11.7:
*
* CPUID returns a value in a model specific register in
* addition to its usual register return values. The
* semantics of CPUID cause it to deposit an update ID value
* in the 64-bit model-specific register at address 08BH
* (IA32_BIOS_SIGN_ID). If no update is present in the
* processor, the value in the MSR remains unmodified.
*
* Use native_cpuid -- this code runs very early and we don't
* want to mess with paravirt.
*/
unsigned int eax = 1, ebx, ecx = 0, edx;
native_cpuid(&eax, &ebx, &ecx, &edx);
}
static int collect_cpu_info_early(struct ucode_cpu_info *uci)
{
unsigned int val[2];
@ -393,7 +413,7 @@ static int collect_cpu_info_early(struct ucode_cpu_info *uci)
native_wrmsrl(MSR_IA32_UCODE_REV, 0);
/* As documented in the SDM: Do a CPUID 1 here */
sync_core();
cpuid_1();
/* get the current revision from MSR 0x8B */
native_rdmsr(MSR_IA32_UCODE_REV, val[0], val[1]);
@ -593,7 +613,7 @@ static int apply_microcode_early(struct ucode_cpu_info *uci, bool early)
native_wrmsrl(MSR_IA32_UCODE_REV, 0);
/* As documented in the SDM: Do a CPUID 1 here */
sync_core();
cpuid_1();
/* get the current revision from MSR 0x8B */
native_rdmsr(MSR_IA32_UCODE_REV, val[0], val[1]);
@ -805,7 +825,7 @@ static int apply_microcode_intel(int cpu)
wrmsrl(MSR_IA32_UCODE_REV, 0);
/* As documented in the SDM: Do a CPUID 1 here */
sync_core();
cpuid_1();
/* get the current revision from MSR 0x8B */
rdmsr(MSR_IA32_UCODE_REV, val[0], val[1]);