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Turn off IBRS on suspend.

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Resume starts CPU from the init state, which clears any loaded
microcode updates.  As result, IBRS MSRs are no longer available,
until the microcode is reloaded.

I have to forcibly clear cpu_stdext_feature3, which assumes that CPUID
leaf 7 reg %ebx does not report anything except Meltdown/Spectre bugs
bits.  If future CPUs add new bits there, hw_ibrs_recalculate() and
identify_cpu1()/identify_cpu2() need to be adjusted for that.

Submitted and tested by:	Michael Danilov <mike.d.ft402@gmail.com>
PR:	227866
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D15236
This commit is contained in:
Konstantin Belousov 2018-04-30 20:18:32 +00:00
parent 47280ef170
commit 986c4ca387
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=333125
2 changed files with 14 additions and 1 deletions
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12
sys/x86/acpica/acpi_wakeup.c
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@ -209,6 +209,10 @@ acpi_sleep_machdep(struct acpi_softc *sc, int state)
{
ACPI_STATUS status;
struct pcb *pcb;
#ifdef __amd64__
struct pcpu *pc;
int i;
#endif
if (sc->acpi_wakeaddr == 0ul)
return (-1); /* couldn't alloc wake memory */
@ -238,6 +242,14 @@ acpi_sleep_machdep(struct acpi_softc *sc, int state)
return (0); /* couldn't sleep */
}
#endif
#ifdef __amd64__
hw_ibrs_active = 0;
cpu_stdext_feature3 = 0;
CPU_FOREACH(i) {
pc = pcpu_find(i);
pc->pc_ibpb_set = 0;
}
#endif
WAKECODE_FIXUP(resume_beep, uint8_t, (acpi_resume_beep != 0));
WAKECODE_FIXUP(reset_video, uint8_t, (acpi_reset_video != 0));

3
sys/x86/include/x86_var.h
View File

@ -83,7 +83,8 @@ extern int _ugssel;
extern int use_xsave;
extern uint64_t xsave_mask;
extern u_int max_apic_id;
extern int pti;
extern int pti;
extern int hw_ibrs_active;
struct pcb;
struct thread;