x86/cpu: Reinitialize IA32_FEAT_CTL MSR on BSP during wakeup (5d510359) · Commits · 戴 / test

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: ("KVM: VMX: Drop initialization of IA32_FEAT_CTL MSR") Reported-by:

Brad Campbell <lists2009@fnarfbargle.com> Signed-off-by:

Sean Christopherson <sean.j.christopherson@intel.com> Signed-off-by:

Borislav Petkov <bp@suse.de> Reviewed-by:

Liam Merwick <liam.merwick@oracle.com> Reviewed-by:

Maxim Levitsky <mlevitsk@redhat.com> Tested-by:

Brad 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

arch/x86/include/asm/cpu.h

+5 −0

Original line number	Diff line number	Diff line
		@@ -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 */

arch/x86/kernel/cpu/centaur.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -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>

arch/x86/kernel/cpu/cpu.h

+0 −4

Original line number	Diff line number	Diff line
		@@ -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 */

arch/x86/kernel/cpu/zhaoxin.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -2,6 +2,7 @@
		#include <linux/sched.h>
		#include <linux/sched/clock.h>

		#include <asm/cpu.h>
		#include <asm/cpufeature.h>

		#include "cpu.h"

arch/x86/power/cpu.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -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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