On 05/18/2012 12:34 PM, Matthias Lange wrote:
> Hi,
>
> I was playing around with kvm's nested virtualization feature on Intel
> VT-x. When trying to access the GUEST_SMBASE (offset 0x4828)field of the
> VMCS I got a "VMREAD/VMWRITE from/to unsupported VMCS component" error.
> According to the Intel manual this field is not optional. The error
> results from the "vmcs_field_to_offset" function in vmx.c because the
> offset of GUEST_SMBASE is not defined.
>
> The following patch adds support for the GUEST_SMBASE field. This allows
> hypervisors running inside kvm read/write access to this field. I have
> tested this to work on a Core i5 machine.
>
> 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 4ff0ab9..0063743 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -285,6 +285,7 @@ struct __packed vmcs12 {
> u32 guest_tr_ar_bytes;
> u32 guest_interruptibility_info;
> u32 guest_activity_state;
> + u32 guest_smbase;
> u32 guest_sysenter_cs;
> u32 host_ia32_sysenter_cs;
> u32 padding32[8]; /* room for future expansion */
> @@ -546,6 +547,7 @@ static unsigned short vmcs_field_to_offset_table[] = {
>
vmcs12 is an ABI, so you can't insert fields at random. Grab one from
padding32.
--
error compiling committee.c: too many arguments to function
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