On Sun, Jun 13, 2010 at 03:24:06PM +0300, Nadav Har'El wrote:
> This patch allows a guest to use the VMXON and VMXOFF instructions, and
> emulates them accordingly. Basically this amounts to checking some
> prerequisites, and then remembering whether the guest has enabled or disabled
> VMX operation.
>
> Signed-off-by: Nadav Har'El <nyh@xxxxxxxxxx>
> ---
> --- .before/arch/x86/kvm/vmx.c 2010-06-13 15:01:28.000000000 +0300
> +++ .after/arch/x86/kvm/vmx.c 2010-06-13 15:01:28.000000000 +0300
> @@ -117,6 +117,16 @@ struct shared_msr_entry {
> u64 mask;
> };
>
> +/* The nested_vmx structure is part of vcpu_vmx, and holds information we need
> + * for correct emulation of VMX (i.e., nested VMX) on this vcpu. For example,
> + * the current VMCS set by L1, a list of the VMCSs used to run the active
> + * L2 guests on the hardware, and more.
> + */
> +struct nested_vmx {
> + /* Has the level1 guest done vmxon? */
> + bool vmxon;
> +};
> +
> struct vcpu_vmx {
> struct kvm_vcpu vcpu;
> struct list_head local_vcpus_link;
> @@ -168,6 +178,9 @@ struct vcpu_vmx {
> u32 exit_reason;
>
> bool rdtscp_enabled;
> +
> + /* Support for guest hypervisors (nested VMX) */
> + struct nested_vmx nested;
> };
>
> static inline struct vcpu_vmx *to_vmx(struct kvm_vcpu *vcpu)
> @@ -3353,6 +3366,93 @@ static int handle_vmx_insn(struct kvm_vc
> return 1;
> }
>
> +/* Emulate the VMXON instruction.
> + * Currently, we just remember that VMX is active, and do not save or even
> + * inspect the argument to VMXON (the so-called "VMXON pointer") because we
> + * do not currently need to store anything in that guest-allocated memory
> + * region. Consequently, VMCLEAR and VMPTRLD also do not verify that the their
> + * argument is different from the VMXON pointer (which the spec says they do).
> + */
> +static int handle_vmon(struct kvm_vcpu *vcpu)
> +{
> + struct kvm_segment cs;
> + struct vcpu_vmx *vmx = to_vmx(vcpu);
> +
> + /* The Intel VMX Instruction Reference lists a bunch of bits that
> + * are prerequisite to running VMXON, most notably CR4.VMXE must be
> + * set to 1. Otherwise, we should fail with #UD. We test these now:
> + */
> + if (!nested) {
> + kvm_queue_exception(vcpu, UD_VECTOR);
> + return 1;
> + }
> +
> + if (!(vcpu->arch.cr4 & X86_CR4_VMXE) ||
> + !(vcpu->arch.cr0 & X86_CR0_PE) ||
kvm_read_cr0_bits, kvm_read_cr4_bits.
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