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KVM: x86: Drop .post_leave_smm(), i.e. the manual post-RSM MMU reset

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Drop the .post_leave_smm() emulator callback, which at this point is just
a wrapper to kvm_mmu_reset_context().  The manual context reset is
unnecessary, because unlike enter_smm() which calls vendor MSR/CR helpers
directly, em_rsm() bounces through the KVM helpers, e.g. kvm_set_cr4(),
which are responsible for processing side effects.  em_rsm() is already
subtly relying on this behavior as it doesn't manually do
kvm_update_cpuid_runtime(), e.g. to recognize CR4.OSXSAVE changes.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210609185619.992058-9-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2021-06-09 11:56:18 -07:00 committed by Paolo Bonzini
parent 1270e647c8
commit 0128116550
3 changed files with 8 additions and 9 deletions
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10
arch/x86/kvm/emulate.c
View File

@ -2591,8 +2591,14 @@ static int em_rsm(struct x86_emulate_ctxt *ctxt)
if (ret != X86EMUL_CONTINUE)
goto emulate_shutdown;
ctxt->ops->post_leave_smm(ctxt);
/*
* Note, the ctxt->ops callbacks are responsible for handling side
* effects when writing MSRs and CRs, e.g. MMU context resets, CPUID
* runtime updates, etc... If that changes, e.g. this flow is moved
* out of the emulator to make it look more like enter_smm(), then
* those side effects need to be explicitly handled for both success
* and shutdown.
*/
return X86EMUL_CONTINUE;
emulate_shutdown:

1
arch/x86/kvm/kvm_emulate.h
View File

@ -233,7 +233,6 @@ struct x86_emulate_ops {
void (*exiting_smm)(struct x86_emulate_ctxt *ctxt);
int (*pre_leave_smm)(struct x86_emulate_ctxt *ctxt,
const char *smstate);
void (*post_leave_smm)(struct x86_emulate_ctxt *ctxt);
void (*triple_fault)(struct x86_emulate_ctxt *ctxt);
int (*set_xcr)(struct x86_emulate_ctxt *ctxt, u32 index, u64 xcr);
};

6
arch/x86/kvm/x86.c
View File

@ -7222,11 +7222,6 @@ static int emulator_pre_leave_smm(struct x86_emulate_ctxt *ctxt,
return static_call(kvm_x86_pre_leave_smm)(emul_to_vcpu(ctxt), smstate);
}
static void emulator_post_leave_smm(struct x86_emulate_ctxt *ctxt)
{
kvm_mmu_reset_context(emul_to_vcpu(ctxt));
}
static void emulator_triple_fault(struct x86_emulate_ctxt *ctxt)
{
kvm_make_request(KVM_REQ_TRIPLE_FAULT, emul_to_vcpu(ctxt));
@ -7280,7 +7275,6 @@ static const struct x86_emulate_ops emulate_ops = {
.get_hflags = emulator_get_hflags,
.exiting_smm = emulator_exiting_smm,
.pre_leave_smm = emulator_pre_leave_smm,
.post_leave_smm = emulator_post_leave_smm,
.triple_fault = emulator_triple_fault,
.set_xcr = emulator_set_xcr,
};