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Message-ID: <20140619135935.GG1695@ERROL.INI.CMU.EDU>
Date: Thu, 19 Jun 2014 09:59:35 -0400
From: "Gabriel L. Somlo" <gsomlo@...il.com>
To: KVM <kvm@...r.kernel.org>
Cc: "Michael S. Tsirkin" <mst@...hat.com>,
Gleb Natapov <gleb@...nel.org>,
Eric Northup <digitaleric@...gle.com>,
Nadav Amit <namit@...technion.ac.il>,
Paolo Bonzini <pbonzini@...hat.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>,
the arch/x86 maintainers <x86@...nel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
nadav.amit@...il.com, joro@...tes.org, agraf@...e.de
Subject: [PATCH] Revert "kvm: x86: emulate monitor and mwait instructions as
nop"
This reverts commit 87c00572ba05aa8c9db118da75c608f47eb10b9e.
OS X <= 10.7.* are the only known guests which realistically required
this functionality. As it turns out, OS X can be told to forego using
monitor/mwait by passing it "idlehalt=0" as a kernel argument, so we're
better off removing this hack from KVM altogether, at least for now.
Signed-off-by: Gabriel L. Somlo <somlo@....edu>
Acked-by: Michael S. Tsirkin <mst@...hat.com>
---
OK, here's the formal proposal to revert my original monitor/mwait hack...
I wish I knew about the "idlehalt=0" before I submitted it, but such is life.
Depending on how those of you higher up the food chain feel, I can tolerate
leaving the hack in if it's never on by default (i.e. no CPUID advertisement),
but would feel better if we could simply undo this until we have a better
solution, something less controversial...
Thanks, and sorry for all the noise,
Gabriel
arch/x86/kvm/cpuid.c | 2 --
arch/x86/kvm/svm.c | 28 ++++++++--------------------
arch/x86/kvm/vmx.c | 20 ++++----------------
3 files changed, 12 insertions(+), 38 deletions(-)
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 38a0afe..17b42fa 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -283,8 +283,6 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
0 /* Reserved */ | f_lm | F(3DNOWEXT) | F(3DNOW);
/* cpuid 1.ecx */
const u32 kvm_supported_word4_x86_features =
- /* NOTE: MONITOR (and MWAIT) are emulated as NOP,
- * but *not* advertised to guests via CPUID ! */
F(XMM3) | F(PCLMULQDQ) | 0 /* DTES64, MONITOR */ |
0 /* DS-CPL, VMX, SMX, EST */ |
0 /* TM2 */ | F(SSSE3) | 0 /* CNXT-ID */ | 0 /* Reserved */ |
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index ec8366c..6b88b6a 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -2763,6 +2763,12 @@ static int xsetbv_interception(struct vcpu_svm *svm)
return 1;
}
+static int invalid_op_interception(struct vcpu_svm *svm)
+{
+ kvm_queue_exception(&svm->vcpu, UD_VECTOR);
+ return 1;
+}
+
static int task_switch_interception(struct vcpu_svm *svm)
{
u16 tss_selector;
@@ -3274,24 +3280,6 @@ static int pause_interception(struct vcpu_svm *svm)
return 1;
}
-static int nop_interception(struct vcpu_svm *svm)
-{
- skip_emulated_instruction(&(svm->vcpu));
- return 1;
-}
-
-static int monitor_interception(struct vcpu_svm *svm)
-{
- printk_once(KERN_WARNING "kvm: MONITOR instruction emulated as NOP!\n");
- return nop_interception(svm);
-}
-
-static int mwait_interception(struct vcpu_svm *svm)
-{
- printk_once(KERN_WARNING "kvm: MWAIT instruction emulated as NOP!\n");
- return nop_interception(svm);
-}
-
static int (*const svm_exit_handlers[])(struct vcpu_svm *svm) = {
[SVM_EXIT_READ_CR0] = cr_interception,
[SVM_EXIT_READ_CR3] = cr_interception,
@@ -3349,8 +3337,8 @@ static int (*const svm_exit_handlers[])(struct vcpu_svm *svm) = {
[SVM_EXIT_CLGI] = clgi_interception,
[SVM_EXIT_SKINIT] = skinit_interception,
[SVM_EXIT_WBINVD] = emulate_on_interception,
- [SVM_EXIT_MONITOR] = monitor_interception,
- [SVM_EXIT_MWAIT] = mwait_interception,
+ [SVM_EXIT_MONITOR] = invalid_op_interception,
+ [SVM_EXIT_MWAIT] = invalid_op_interception,
[SVM_EXIT_XSETBV] = xsetbv_interception,
[SVM_EXIT_NPF] = pf_interception,
};
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 801332e..163958f 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -5672,24 +5672,12 @@ static int handle_pause(struct kvm_vcpu *vcpu)
return 1;
}
-static int handle_nop(struct kvm_vcpu *vcpu)
+static int handle_invalid_op(struct kvm_vcpu *vcpu)
{
- skip_emulated_instruction(vcpu);
+ kvm_queue_exception(vcpu, UD_VECTOR);
return 1;
}
-static int handle_mwait(struct kvm_vcpu *vcpu)
-{
- printk_once(KERN_WARNING "kvm: MWAIT instruction emulated as NOP!\n");
- return handle_nop(vcpu);
-}
-
-static int handle_monitor(struct kvm_vcpu *vcpu)
-{
- printk_once(KERN_WARNING "kvm: MONITOR instruction emulated as NOP!\n");
- return handle_nop(vcpu);
-}
-
/*
* To run an L2 guest, we need a vmcs02 based on the L1-specified vmcs12.
* We could reuse a single VMCS for all the L2 guests, but we also want the
@@ -6651,8 +6639,8 @@ static int (*const kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = {
[EXIT_REASON_EPT_VIOLATION] = handle_ept_violation,
[EXIT_REASON_EPT_MISCONFIG] = handle_ept_misconfig,
[EXIT_REASON_PAUSE_INSTRUCTION] = handle_pause,
- [EXIT_REASON_MWAIT_INSTRUCTION] = handle_mwait,
- [EXIT_REASON_MONITOR_INSTRUCTION] = handle_monitor,
+ [EXIT_REASON_MWAIT_INSTRUCTION] = handle_invalid_op,
+ [EXIT_REASON_MONITOR_INSTRUCTION] = handle_invalid_op,
[EXIT_REASON_INVEPT] = handle_invept,
};
--
1.9.3
--
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