diff mbox

[v4,01/13] nEPT: Support LOAD_IA32_EFER entry/exit controls for L1

Message ID 1374750001-28527-2-git-send-email-gleb@redhat.com (mailing list archive)
State New, archived
Headers show

Commit Message

Gleb Natapov July 25, 2013, 10:59 a.m. UTC 
From: Nadav Har'El <nyh@il.ibm.com>

Recent KVM, since http://kerneltrap.org/mailarchive/linux-kvm/2010/5/2/6261577
switch the EFER MSR when EPT is used and the host and guest have different
NX bits. So if we add support for nested EPT (L1 guest using EPT to run L2)
and want to be able to run recent KVM as L1, we need to allow L1 to use this
EFER switching feature.

To do this EFER switching, KVM uses VM_ENTRY/EXIT_LOAD_IA32_EFER if available,
and if it isn't, it uses the generic VM_ENTRY/EXIT_MSR_LOAD. This patch adds
support for the former (the latter is still unsupported).

Nested entry and exit emulation (prepare_vmcs_02 and load_vmcs12_host_state,
respectively) already handled VM_ENTRY/EXIT_LOAD_IA32_EFER correctly. So all
that's left to do in this patch is to properly advertise this feature to L1.

Note that vmcs12's VM_ENTRY/EXIT_LOAD_IA32_EFER are emulated by L0, by using
vmx_set_efer (which itself sets one of several vmcs02 fields), so we always
support this feature, regardless of whether the host supports it.

Signed-off-by: Nadav Har'El <nyh@il.ibm.com>
Signed-off-by: Jun Nakajima <jun.nakajima@intel.com>
Signed-off-by: Xinhao Xu <xinhao.xu@intel.com>
Signed-off-by: Yang Zhang <yang.z.zhang@Intel.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
---
 arch/x86/kvm/vmx.c |   23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

Comments

Paolo Bonzini July 29, 2013, 8:32 a.m. UTC | #1 
Il 25/07/2013 12:59, Gleb Natapov ha scritto:
> +	 * we should use its exit controls. Note that IA32_MODE, LOAD_IA32_EFER
> +	 * bits are further modified by vmx_set_efer() below.

IA32E_MODE, but the last sentence is not relevant anyway for this
vmcs_write32; in fact, the next command basically duplicates it.

This can be fixed while applying.

Paolo

> +	 */
> +	vmcs_write32(VM_EXIT_CONTROLS, vmcs_config.vmexit_ctrl);
> +
> +	/* vmcs12's VM_ENTRY_LOAD_IA32_EFER and VM_ENTRY_IA32E_MODE are
> +	 * emulated by vmx_set_efer(), below.
> +	 */
> +	vmcs_write32(VM_ENTRY_CONTROLS,
> +		(vmcs12->vm_entry_controls & ~VM_ENTRY_LOAD_IA32_EFER &
> +			~VM_ENTRY_IA32E_MODE) |
>  		(vmcs_config.vmentry_ctrl & ~VM_ENTRY_IA32E_MODE));
>  
>  	if (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_IA32_PAT)
> -- 1.7.10.4

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Gleb Natapov July 29, 2013, 1:12 p.m. UTC | #2 
On Mon, Jul 29, 2013 at 10:32:58AM +0200, Paolo Bonzini wrote:
> Il 25/07/2013 12:59, Gleb Natapov ha scritto:
> > +	 * we should use its exit controls. Note that IA32_MODE, LOAD_IA32_EFER
> > +	 * bits are further modified by vmx_set_efer() below.
> 
> IA32E_MODE, but the last sentence is not relevant anyway for this
> vmcs_write32; in fact, the next command basically duplicates it.
> 
IA32E_MODE is not relevant, it never changes in VM_EXIT_CONTROLS, but
LOAD_IA32_EFER refers to VM_EXIT_LOAD_IA32_EFER, which can be set by
vmx_set_efer() and is different from VM_ENTRY_LOAD_IA32_EFER that
comment bellow talks about.

> This can be fixed while applying.
> 
> Paolo
> 
> > +	 */
> > +	vmcs_write32(VM_EXIT_CONTROLS, vmcs_config.vmexit_ctrl);
> > +
> > +	/* vmcs12's VM_ENTRY_LOAD_IA32_EFER and VM_ENTRY_IA32E_MODE are
> > +	 * emulated by vmx_set_efer(), below.
> > +	 */
> > +	vmcs_write32(VM_ENTRY_CONTROLS,
> > +		(vmcs12->vm_entry_controls & ~VM_ENTRY_LOAD_IA32_EFER &
> > +			~VM_ENTRY_IA32E_MODE) |
> >  		(vmcs_config.vmentry_ctrl & ~VM_ENTRY_IA32E_MODE));
> >  
> >  	if (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_IA32_PAT)
> > -- 1.7.10.4

--
			Gleb.
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Paolo Bonzini July 29, 2013, 2:13 p.m. UTC | #3 
Il 29/07/2013 15:12, Gleb Natapov ha scritto:
>> Il 25/07/2013 12:59, Gleb Natapov ha scritto:
>>> > > +	 * we should use its exit controls. Note that IA32_MODE, LOAD_IA32_EFER
>>> > > +	 * bits are further modified by vmx_set_efer() below.
>> > 
>> > IA32E_MODE, but the last sentence is not relevant anyway for this
>> > vmcs_write32; in fact, the next command basically duplicates it.
>> > 
> IA32E_MODE is not relevant, it never changes in VM_EXIT_CONTROLS, but
> LOAD_IA32_EFER refers to VM_EXIT_LOAD_IA32_EFER, which can be set by
> vmx_set_efer() and is different from VM_ENTRY_LOAD_IA32_EFER that
> comment bellow talks about.
> 

Yes.  Just fix the comment so that it is clear.

Paolo
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diff mbox

Patch

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index e999dc7..1e9437f 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2198,7 +2198,8 @@  static __init void nested_vmx_setup_ctls_msrs(void)
 #else
 	nested_vmx_exit_ctls_high = 0;
 #endif
-	nested_vmx_exit_ctls_high |= VM_EXIT_ALWAYSON_WITHOUT_TRUE_MSR;
+	nested_vmx_exit_ctls_high |= (VM_EXIT_ALWAYSON_WITHOUT_TRUE_MSR |
+				      VM_EXIT_LOAD_IA32_EFER);
 
 	/* entry controls */
 	rdmsr(MSR_IA32_VMX_ENTRY_CTLS,
@@ -2207,8 +2208,8 @@  static __init void nested_vmx_setup_ctls_msrs(void)
 	nested_vmx_entry_ctls_low = VM_ENTRY_ALWAYSON_WITHOUT_TRUE_MSR;
 	nested_vmx_entry_ctls_high &=
 		VM_ENTRY_LOAD_IA32_PAT | VM_ENTRY_IA32E_MODE;
-	nested_vmx_entry_ctls_high |= VM_ENTRY_ALWAYSON_WITHOUT_TRUE_MSR;
-
+	nested_vmx_entry_ctls_high |= (VM_ENTRY_ALWAYSON_WITHOUT_TRUE_MSR |
+				       VM_ENTRY_LOAD_IA32_EFER);
 	/* cpu-based controls */
 	rdmsr(MSR_IA32_VMX_PROCBASED_CTLS,
 		nested_vmx_procbased_ctls_low, nested_vmx_procbased_ctls_high);
@@ -7529,10 +7530,18 @@  static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
 	vcpu->arch.cr0_guest_owned_bits &= ~vmcs12->cr0_guest_host_mask;
 	vmcs_writel(CR0_GUEST_HOST_MASK, ~vcpu->arch.cr0_guest_owned_bits);
 
-	/* Note: IA32_MODE, LOAD_IA32_EFER are modified by vmx_set_efer below */
-	vmcs_write32(VM_EXIT_CONTROLS,
-		vmcs12->vm_exit_controls | vmcs_config.vmexit_ctrl);
-	vmcs_write32(VM_ENTRY_CONTROLS, vmcs12->vm_entry_controls |
+	/* L2->L1 exit controls are emulated - the hardware exit is to L0 so
+	 * we should use its exit controls. Note that IA32_MODE, LOAD_IA32_EFER
+	 * bits are further modified by vmx_set_efer() below.
+	 */
+	vmcs_write32(VM_EXIT_CONTROLS, vmcs_config.vmexit_ctrl);
+
+	/* vmcs12's VM_ENTRY_LOAD_IA32_EFER and VM_ENTRY_IA32E_MODE are
+	 * emulated by vmx_set_efer(), below.
+	 */
+	vmcs_write32(VM_ENTRY_CONTROLS,
+		(vmcs12->vm_entry_controls & ~VM_ENTRY_LOAD_IA32_EFER &
+			~VM_ENTRY_IA32E_MODE) |
 		(vmcs_config.vmentry_ctrl & ~VM_ENTRY_IA32E_MODE));
 
 	if (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_IA32_PAT)