This is a note to let you know that I've just added the patch titled
KVM: x86: Drop .post_leave_smm(), i.e. the manual post-RSM MMU reset
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-x86-drop-.post_leave_smm-i.e.-the-manual-post-rs.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 44547012febf343ca7bf53890bbe2a42c22aaa0d
Author: Sean Christopherson <seanjc@xxxxxxxxxx>
Date: Wed Jun 9 11:56:18 2021 -0700
KVM: x86: Drop .post_leave_smm(), i.e. the manual post-RSM MMU reset
[ Upstream commit 0128116550acf52043a0aa5cca3caa85e3853aca ]
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@xxxxxxxxxx>
Message-Id: <20210609185619.992058-9-seanjc@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Stable-dep-of: 055f37f84e30 ("KVM: x86: emulator: update the emulation mode after rsm")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 2e6d7640c4ed..d5da89271318 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2741,8 +2741,14 @@ 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 148ba21d0646..3650db9e5ed5 100644
--- a/arch/x86/kvm/kvm_emulate.h
+++ b/arch/x86/kvm/kvm_emulate.h
@@ -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);
};
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ef43bfa1b3a8..e04e97b0661c 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7013,11 +7013,6 @@ static int emulator_pre_leave_smm(struct x86_emulate_ctxt *ctxt,
return kvm_x86_ops.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));
@@ -7072,7 +7067,6 @@ 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,
};
