[PATCH 01/12] Subject: [PATCH 01/10] nEPT: Support LOAD_IA32_EFER entry/exit controls for L1

[PATCH 01/12] Subject: [PATCH 01/10] nEPT: Support LOAD_IA32_EFER entry/exit controls for L1

[Nakajima, Jun]

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>

modified:   arch/x86/kvm/vmx.c
---
 arch/x86/kvm/vmx.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 6667042..9e0ec9d 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2057,6 +2057,7 @@ static __init void nested_vmx_setup_ctls_msrs(void)
 #else
  nested_vmx_exit_ctls_high = 0;
 #endif
+ nested_vmx_exit_ctls_high |= VM_EXIT_LOAD_IA32_EFER;

  /* entry controls */
  rdmsr(MSR_IA32_VMX_ENTRY_CTLS,
@@ -2064,6 +2065,7 @@ static __init void nested_vmx_setup_ctls_msrs(void)
  nested_vmx_entry_ctls_low = 0;
  nested_vmx_entry_ctls_high &=
  VM_ENTRY_LOAD_IA32_PAT | VM_ENTRY_IA32E_MODE;
+ nested_vmx_entry_ctls_high |= VM_ENTRY_LOAD_IA32_EFER;

  /* cpu-based controls */
  rdmsr(MSR_IA32_VMX_PROCBASED_CTLS,
@@ -7050,10 +7052,18 @@ 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)
--
1.8.2.1.610.g562af5b

Re: [PATCH 01/12] Subject: [PATCH 01/10] nEPT: Support LOAD_IA32_EFER entry/exit controls for L1

[Gleb Natapov]

All the patches are mangled by your email client. Please use "git
send-email --thread" to send them.

On Thu, Apr 25, 2013 at 12:50:19AM -0700, Nakajima, Jun wrote:
> 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>
> 
> modified:   arch/x86/kvm/vmx.c
> ---
>  arch/x86/kvm/vmx.c | 18 ++++++++++++++----
>  1 file changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 6667042..9e0ec9d 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -2057,6 +2057,7 @@ static __init void nested_vmx_setup_ctls_msrs(void)
>  #else
>   nested_vmx_exit_ctls_high = 0;
>  #endif
> + nested_vmx_exit_ctls_high |= VM_EXIT_LOAD_IA32_EFER;
> 
>   /* entry controls */
>   rdmsr(MSR_IA32_VMX_ENTRY_CTLS,
> @@ -2064,6 +2065,7 @@ static __init void nested_vmx_setup_ctls_msrs(void)
>   nested_vmx_entry_ctls_low = 0;
>   nested_vmx_entry_ctls_high &=
>   VM_ENTRY_LOAD_IA32_PAT | VM_ENTRY_IA32E_MODE;
> + nested_vmx_entry_ctls_high |= VM_ENTRY_LOAD_IA32_EFER;
> 
>   /* cpu-based controls */
>   rdmsr(MSR_IA32_VMX_PROCBASED_CTLS,
> @@ -7050,10 +7052,18 @@ 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)
> --
> 1.8.2.1.610.g562af5b
> --
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--
			Gleb.