Commit 8a19394f authored by Sean Christopherson's avatar Sean Christopherson Committed by Sasha Levin
Browse files

x86/cpu: Reinitialize IA32_FEAT_CTL MSR on BSP during wakeup

commit 5d510359 upstream.

Reinitialize IA32_FEAT_CTL on the BSP during wakeup to handle the case
where firmware doesn't initialize or save/restore across S3.  This fixes
a bug where IA32_FEAT_CTL is left uninitialized and results in VMXON
taking a #GP due to VMX not being fully enabled, i.e. breaks KVM.

Use init_ia32_feat_ctl() to "restore" IA32_FEAT_CTL as it already deals
with the case where the MSR is locked, and because APs already redo
init_ia32_feat_ctl() during suspend by virtue of the SMP boot flow being
used to reinitialize APs upon wakeup.  Do the call in the early wakeup
flow to avoid dependencies in the syscore_ops chain, e.g. simply adding
a resume hook is not guaranteed to work, as KVM does VMXON in its own
resume hook, kvm_resume(), when KVM has active guests.

Fixes: 21bd3467

 ("KVM: VMX: Drop initialization of IA32_FEAT_CTL MSR")
Reported-by: default avatarBrad Campbell <lists2009@fnarfbargle.com>
Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Reviewed-by: default avatarLiam Merwick <liam.merwick@oracle.com>
Reviewed-by: default avatarMaxim Levitsky <mlevitsk@redhat.com>
Tested-by: default avatarBrad Campbell <lists2009@fnarfbargle.com>
Cc: stable@vger.kernel.org # v5.6
Link: https://lkml.kernel.org/r/20200608174134.11157-1-sean.j.christopherson@intel.com

Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 8e612264
......@@ -58,4 +58,9 @@ static inline bool handle_guest_split_lock(unsigned long ip)
return false;
}
#endif
#ifdef CONFIG_IA32_FEAT_CTL
void init_ia32_feat_ctl(struct cpuinfo_x86 *c);
#else
static inline void init_ia32_feat_ctl(struct cpuinfo_x86 *c) {}
#endif
#endif /* _ASM_X86_CPU_H */
......@@ -3,6 +3,7 @@
#include <linux/sched.h>
#include <linux/sched/clock.h>
#include <asm/cpu.h>
#include <asm/cpufeature.h>
#include <asm/e820/api.h>
#include <asm/mtrr.h>
......
......@@ -81,8 +81,4 @@ extern void update_srbds_msr(void);
extern u64 x86_read_arch_cap_msr(void);
#ifdef CONFIG_IA32_FEAT_CTL
void init_ia32_feat_ctl(struct cpuinfo_x86 *c);
#endif
#endif /* ARCH_X86_CPU_H */
......@@ -2,6 +2,7 @@
#include <linux/sched.h>
#include <linux/sched/clock.h>
#include <asm/cpu.h>
#include <asm/cpufeature.h>
#include "cpu.h"
......
......@@ -193,6 +193,8 @@ static void fix_processor_context(void)
*/
static void notrace __restore_processor_state(struct saved_context *ctxt)
{
struct cpuinfo_x86 *c;
if (ctxt->misc_enable_saved)
wrmsrl(MSR_IA32_MISC_ENABLE, ctxt->misc_enable);
/*
......@@ -263,6 +265,10 @@ static void notrace __restore_processor_state(struct saved_context *ctxt)
mtrr_bp_restore();
perf_restore_debug_store();
msr_restore_context(ctxt);
c = &cpu_data(smp_processor_id());
if (cpu_has(c, X86_FEATURE_MSR_IA32_FEAT_CTL))
init_ia32_feat_ctl(c);
}
/* Needed by apm.c */
......
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