From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
syzbot+fb0b6a7e8713aeb0319c@syzkaller.appspotmail.com
Subject: [PATCH 8/9] KVM: x86: Drop .post_leave_smm(), i.e. the manual post-RSM MMU reset
Date: Wed, 9 Jun 2021 11:56:18 -0700 [thread overview]
Message-ID: <20210609185619.992058-9-seanjc@google.com> (raw)
In-Reply-To: <20210609185619.992058-1-seanjc@google.com>
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>
---
arch/x86/kvm/emulate.c | 10 ++++++++--
arch/x86/kvm/kvm_emulate.h | 1 -
arch/x86/kvm/x86.c | 6 ------
3 files changed, 8 insertions(+), 9 deletions(-)
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 9e0d5900c011..34c9f785d715 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2694,8 +2694,14 @@ 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:
diff --git a/arch/x86/kvm/kvm_emulate.h b/arch/x86/kvm/kvm_emulate.h
index b620782c1fb5..31dc7ca4ff2b 100644
--- a/arch/x86/kvm/kvm_emulate.h
+++ b/arch/x86/kvm/kvm_emulate.h
@@ -232,7 +232,6 @@ 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);
};
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 06f3be2d170b..347849caf1df 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7112,11 +7112,6 @@ 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));
@@ -7170,7 +7165,6 @@ 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,
};
--
2.32.0.rc1.229.g3e70b5a671-goog
next prev parent reply other threads:[~2021-06-09 18:56 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-09 18:56 [PATCH 0/9] KVM: x86: Fix NULL pointer #GP due to RSM bug Sean Christopherson
2021-06-09 18:56 ` [PATCH 1/9] KVM: x86: Immediately reset the MMU context when the SMM flag is cleared Sean Christopherson
2021-06-10 13:19 ` Paolo Bonzini
2021-06-09 18:56 ` [PATCH 2/9] KVM: x86: Emulate triple fault shutdown if RSM emulation fails Sean Christopherson
2021-06-10 8:26 ` Vitaly Kuznetsov
2021-06-10 13:29 ` Paolo Bonzini
2021-06-10 15:28 ` Sean Christopherson
2021-06-10 15:30 ` Sean Christopherson
2021-06-11 11:42 ` Vitaly Kuznetsov
2021-06-10 13:23 ` Paolo Bonzini
2021-06-09 18:56 ` [PATCH 3/9] KVM: x86: Replace .set_hflags() with dedicated .exiting_smm() helper Sean Christopherson
2021-06-09 18:56 ` [PATCH 4/9] KVM: x86: Invoke kvm_smm_changed() immediately after clearing SMM flag Sean Christopherson
2021-06-09 18:56 ` [PATCH 5/9] KVM: x86: Move (most) SMM hflags modifications into kvm_smm_changed() Sean Christopherson
2021-06-09 18:56 ` [PATCH 6/9] KVM: x86: Move "entering SMM" tracepoint " Sean Christopherson
2021-06-09 18:56 ` [PATCH 7/9] KVM: x86: Rename SMM tracepoint to make it reflect reality Sean Christopherson
2021-06-09 18:56 ` Sean Christopherson [this message]
2021-06-09 18:56 ` [PATCH 9/9] KVM: x86: Drop "pre_" from enter/leave_smm() helpers Sean Christopherson
2021-06-10 13:28 ` [PATCH 0/9] KVM: x86: Fix NULL pointer #GP due to RSM bug Paolo Bonzini
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