Re: [PATCH RFC 2/2] Hardware task switching support

[Avi Kivity <avi@qumranet.com>]

Izik Eidus wrote:
> >From 6a7207a0f3ee8af6ebafcec9d40a75b87f00a129 Mon Sep 17 00:00:00 2001
> From: Izik Eidus <izike@qumranet.com>
> Date: Thu, 13 Mar 2008 02:34:21 +0200
> Subject: [PATCH] KVM: hardware task switching support
>
> Signed-off-by: Izik Eidus <izike@qumranet.com>
> ---
>  arch/x86/kvm/svm.c         |   11 +-
>  arch/x86/kvm/tss_segment.h |   59 +++++++
>  arch/x86/kvm/vmx.c         |   15 ++
>  arch/x86/kvm/x86.c         |  385 ++++++++++++++++++++++++++++++++++++++++++++
>  include/asm-x86/kvm_host.h |    2 +
>  5 files changed, 469 insertions(+), 3 deletions(-)
>  create mode 100644 arch/x86/kvm/tss_segment.h
>
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 4e1dd61..be78278 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -1121,9 +1121,14 @@ static int invalid_op_interception(struct vcpu_svm *svm,
>  static int task_switch_interception(struct vcpu_svm *svm,
>  				    struct kvm_run *kvm_run)
>  {
> -	pr_unimpl(&svm->vcpu, "%s: task switch is unsupported\n", __func__);
> -	kvm_run->exit_reason = KVM_EXIT_UNKNOWN;
> -	return 0;
> +	u16 tss_selector;
> +
> +	tss_selector = (u16)svm->vmcb->control.exit_info_1;
> +	if(svm->vmcb->control.exit_info_2 & ((unsigned long)1 << 36))
> +		return kvm_task_switch(&svm->vcpu, tss_selector, 1);
> +	if(svm->vmcb->control.exit_info_2 & ((unsigned long)1 << 38))
> +		return kvm_task_switch(&svm->vcpu, tss_selector, 2);
> +	return kvm_task_switch(&svm->vcpu, tss_selector, 0);
>   

space after if.  Change the magic numbers (36, 38, 0, 1, 2) inuo 
constants in svm.h and kvm_host.h. (unsigned long)1 << 36 will break on 
i386 (needs 1ULL << 36).

>  }
>  
>  static int cpuid_interception(struct vcpu_svm *svm, struct kvm_run *kvm_run)
> diff --git a/arch/x86/kvm/tss_segment.h b/arch/x86/kvm/tss_segment.h
> new file mode 100644
> index 0000000..622aa10
> --- /dev/null
> +++ b/arch/x86/kvm/tss_segment.h
>   

"tss" already has "segment" in it.  call it just tss.h.

> +
> +/* allowed just for 8 bytes segments */
> +static int load_guest_segment_descriptor(struct kvm_vcpu *vcpu, u16 selector,
> +			      struct desc_struct *seg_desc)
> +{
> +	struct descriptor_table gdt_ldt;
> +	u16 index = selector >> 3;
> +
> +	if (selector & 1 << 2)
> +		kvm_x86_ops->get_ldt(vcpu, &gdt_ldt);
> +	else
> +		kvm_x86_ops->get_gdt(vcpu, &gdt_ldt);
> +	if (gdt_ldt.limit < index * 8 + 7)
> +		return 1;
>   

This part can be in a helper function shared with load_ and 
save_guest_segment_descriptor.  Maybe rename to read_ and write_ to 
avoid confusion.

> +
> +static int load_tss_segment32(struct kvm_vcpu *vcpu,
> +			      struct desc_struct *seg_desc,
> +			      struct tss_segment_32 *tss)
> +{
> +	u32 base_addr;
> +
> +	base_addr = seg_desc->base0;
> +	base_addr |= (seg_desc->base1 << 16);
> +	base_addr |= (seg_desc->base2 << 24);
>   

A helper, again.

> +static void save_state_to_tss32(struct kvm_vcpu *vcpu,
> +				struct tss_segment_32 *tss)
> +{
> +	struct kvm_segment kvm_seg;
> +
> +	tss->cr3 = vcpu->arch.cr3;
> +	tss->eip = vcpu->arch.rip;
> +	tss->eflags = kvm_x86_ops->get_rflags(vcpu);
> +	tss->eax = vcpu->arch.regs[VCPU_REGS_RAX];
> +	tss->ecx = vcpu->arch.regs[VCPU_REGS_RCX];
> +	tss->edx = vcpu->arch.regs[VCPU_REGS_RDX];
> +	tss->ebx = vcpu->arch.regs[VCPU_REGS_RBX];
> +	tss->esp = vcpu->arch.regs[VCPU_REGS_RSP];
> +	tss->ebp = vcpu->arch.regs[VCPU_REGS_RBP];
> +	tss->esi = vcpu->arch.regs[VCPU_REGS_RSI];
> +	tss->edi = vcpu->arch.regs[VCPU_REGS_RDI];
> +	
> +	get_segment(vcpu, &kvm_seg, VCPU_SREG_ES);
> +	tss->es = kvm_seg.selector;
>   

tss->es = get_segment_selector(vcpu, VCPU_SREG_ES);

> +	load_guest_segment_descriptor(vcpu, tss->ldt_selector,
> +				      &seg_desc);
> +	seg_desct_to_kvm_desct(&seg_desc, tss->ldt_selector,
> +			       &kvm_seg);
> +	set_segment(vcpu, &kvm_seg, VCPU_SREG_LDTR);
> +
> +	load_guest_segment_descriptor(vcpu, tss->es, &seg_desc);
> +	seg_desct_to_kvm_desct(&seg_desc, tss->es, &kvm_seg);
> +	kvm_seg.type |= 1;
> +	if (!kvm_seg.s)
> +		kvm_seg.unusable = 1;
> +	set_segment(vcpu, &kvm_seg, VCPU_SREG_ES);
>   

Wrap these into a helper.


-- 
error compiling committee.c: too many arguments to function


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