Re: [Xen-devel] [PATCH 10/13] Nested Virtualization: interrupts (svm specific)

[Tim Deegan <Tim.Deegan@xxxxxxxxxx>]

At 18:44 +0000 on 12 Nov (1289587459), Christoph Egger wrote:
> diff -r 3bfc06e2e41a -r b18448601670 xen/arch/x86/hvm/svm/nestedsvm.c
> --- a/xen/arch/x86/hvm/svm/nestedsvm.c
> +++ b/xen/arch/x86/hvm/svm/nestedsvm.c
> @@ -24,6 +24,30 @@
>  #include <asm/hvm/svm/nestedsvm.h>
>  #include <asm/hvm/svm/svmdebug.h>
>  #include <asm/paging.h> /* paging_mode_hap */
> +#include <asm/event.h> /* for local_event_delivery_(en|dis)able */
> +
> +static int
> +nestedsvm_vcpu_clgi(struct vcpu *v)
> +{
> +    struct nestedsvm *svm = &vcpu_nestedsvm(v);
> +
> +    /* clear gif flag */
> +    svm->ns_gif = 0;
> +    local_event_delivery_disable(); /* mask events for PV drivers */

This function, and the stgi one below, can only operate safely on
current; if you want to keep the argument for performance then maybe
ASSERT(v == current) for sanity.

> +    return 0;

Also, since they only ever return 0, please make them return void
instead. 

> +}
> +
> +static int
> +nestedsvm_vcpu_stgi(struct vcpu *v)
> +{
> +    struct nestedsvm *svm = &vcpu_nestedsvm(v);
> +
> +    /* Always set the GIF to make hvm_interrupt_blocked work. */
> +    svm->ns_gif = 1;
> +
> +    local_event_delivery_enable(); /* unmask events for PV drivers */
> +    return 0;
> +}

> +void svm_vmexit_do_stgi(struct cpu_user_regs *regs, struct vcpu *v)
> +{
> +    int ret;
> +    unsigned int inst_len;
> +
> +    if ( !nestedhvm_enabled(v->domain) ) {
> +        hvm_inject_exception(TRAP_invalid_op, HVM_DELIVER_NO_ERROR_CODE, 0);
> +        return;
> +    }
> +
> +    if ( (inst_len = __get_instruction_length(v, INSTR_STGI)) == 0 )
> +        return;
> +
> +    ret = nestedsvm_vcpu_stgi(v);
> +    if (ret)
> +        /* On failure, nestedsvm_vcpu_stgi injected an exception,
> +         * almost a #GP or #UD.

No, it never fails and always returns 0. :)  Likewise below.

Cheers,

Tim.

> +         */
> +       return;
> +
> +    __update_guest_eip(regs, inst_len);
> +}
> +
> +void svm_vmexit_do_clgi(struct cpu_user_regs *regs, struct vcpu *v)
> +{
> +    int ret;
> +    struct vmcb_struct *vmcb = v->arch.hvm_svm.vmcb;
> +    unsigned int inst_len;
> +
> +    if ( !nestedhvm_enabled(v->domain) ) {
> +        hvm_inject_exception(TRAP_invalid_op, HVM_DELIVER_NO_ERROR_CODE, 0);
> +        return;
> +    }
> +
> +    if ( (inst_len = __get_instruction_length(v, INSTR_CLGI)) == 0 )
> +        return;
> +
> +    ret = nestedsvm_vcpu_clgi(v);
> +    if (ret)
> +        /* On failure, nestedsvm_vcpu_clgi injected an exception,
> +         * almost a #GP or #UD.
> +         */
> +        return;
> +
> +    /* After a CLGI no interrupts should come */
> +    vmcb->vintr.fields.irq = 0;
> +    vmcb->general1_intercepts &= ~GENERAL1_INTERCEPT_VINTR;
> +
> +    __update_guest_eip(regs, inst_len);
> +}

-- 
Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, Xen Platform Team
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)

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