Re: [PATCH] Support for GUEST_SMBASE vmcs field for nested virtualization

[Matthias Lange <mlange@sec.t-labs.tu-berlin.de>]

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On Wed, Jun 06, 2012 at 03:12:56PM +0300, Avi Kivity wrote:
> On 06/06/2012 02:37 PM, Matthias Lange wrote:
> > @@ -6536,6 +6538,7 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
> >  	vmcs_write32(GUEST_INTERRUPTIBILITY_INFO,
> >  		vmcs12->guest_interruptibility_info);
> >  	vmcs_write32(GUEST_ACTIVITY_STATE, vmcs12->guest_activity_state);
> > +	vmcs_write32(GUEST_SMBASE, vmcs12->guest_smbase);
> >  	vmcs_write32(GUEST_SYSENTER_CS, vmcs12->guest_sysenter_cs);
> >  	vmcs_writel(GUEST_DR7, vmcs12->guest_dr7);
> >  	vmcs_writel(GUEST_RFLAGS, vmcs12->guest_rflags);
> > @@ -6937,6 +6940,7 @@ void prepare_vmcs12(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
> >  	vmcs12->guest_idtr_base = vmcs_readl(GUEST_IDTR_BASE);
> >  
> >  	vmcs12->guest_activity_state = vmcs_read32(GUEST_ACTIVITY_STATE);
> > +	vmcs12->guest_smbase = vmcs_read32(GUEST_SMBASE);
> >  	vmcs12->guest_interruptibility_info =
> >  		vmcs_read32(GUEST_INTERRUPTIBILITY_INFO);
> >  	vmcs12->guest_pending_dbg_exceptions =
> 
> 
> I missed this earlier: I don't think we need this.  If we do implement
> SMM, anything touching SMBASE (SMI delivery and RSM) will be emulated,
> so we don't need anything in vmcs02 (just vmcs12, which is handled by
> the code above).

I updated the patch according to your comments.

Matthias.


-- 
Dipl.-Inf. Matthias Lange <mlange@sec.t-labs.tu-berlin.de>
Security in Telecommunications
TU Berlin / Telekom Innovation Laboratories
Ernst-Reuter-Platz 7, 10587 Berlin
Phone: +49 - 30 - 8353 58 553
Mobile: +49 - 160 - 587 28 07
Web: http://www.t-labs.tu-berlin.de/sect

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>From bdcb7c52a5f4202d9322cc85a88a83af596cf11d Mon Sep 17 00:00:00 2001
From: Matthias Lange <mlange@sec.t-labs.tu-berlin.de>
Date: Fri, 18 May 2012 10:58:00 +0200
Subject: [PATCH] Add support for the GUEST_SMBASE VMCS field for Intel VT-x
 in the case of nested virtualization. - I take a slot from
 the padding32 area to insert the field into the vmcs12  
 struct

---
 arch/x86/include/asm/vmx.h |    1 +
 arch/x86/kvm/vmx.c         |    5 ++++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index 31f180c..6a14720 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -194,6 +194,7 @@ enum vmcs_field {
 	GUEST_TR_AR_BYTES               = 0x00004822,
 	GUEST_INTERRUPTIBILITY_INFO     = 0x00004824,
 	GUEST_ACTIVITY_STATE            = 0X00004826,
+	GUEST_SMBASE			= 0x00004828,
 	GUEST_SYSENTER_CS               = 0x0000482A,
 	HOST_IA32_SYSENTER_CS           = 0x00004c00,
 	CR0_GUEST_HOST_MASK             = 0x00006000,
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 32eb588..7c703c6 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -294,7 +294,8 @@ struct __packed vmcs12 {
 	u32 guest_activity_state;
 	u32 guest_sysenter_cs;
 	u32 host_ia32_sysenter_cs;
-	u32 padding32[8]; /* room for future expansion */
+	u32 guest_smbase;
+	u32 padding32[7]; /* room for future expansion */
 	u16 virtual_processor_id;
 	u16 guest_es_selector;
 	u16 guest_cs_selector;
@@ -556,6 +557,7 @@ static unsigned short vmcs_field_to_offset_table[] = {
 	FIELD(GUEST_TR_BASE, guest_tr_base),
 	FIELD(GUEST_GDTR_BASE, guest_gdtr_base),
 	FIELD(GUEST_IDTR_BASE, guest_idtr_base),
+	FIELD(GUEST_SMBASE, guest_smbase),
 	FIELD(GUEST_DR7, guest_dr7),
 	FIELD(GUEST_RSP, guest_rsp),
 	FIELD(GUEST_RIP, guest_rip),
@@ -6937,6 +6939,7 @@ void prepare_vmcs12(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
 	vmcs12->guest_idtr_base = vmcs_readl(GUEST_IDTR_BASE);
 
 	vmcs12->guest_activity_state = vmcs_read32(GUEST_ACTIVITY_STATE);
+	vmcs12->guest_smbase = vmcs_read32(GUEST_SMBASE);
 	vmcs12->guest_interruptibility_info =
 		vmcs_read32(GUEST_INTERRUPTIBILITY_INFO);
 	vmcs12->guest_pending_dbg_exceptions =
-- 
1.7.9.5