Re: [Xen-devel] [PATCH 14/18] Nested Virtualization: svm specific implementation

[Tim Deegan <Tim.Deegan@xxxxxxxxxx>]

> +static int nsvm_vmrun_permissionmap(struct vcpu *v)
> +{
> +    struct arch_svm_struct *arch_svm = &v->arch.hvm_svm;
> +    struct vmcb_struct *ns_vmcb = VCPU_NESTEDHVM(v).nh_vmcb;
> +    struct vmcb_struct *host_vmcb = arch_svm->vmcb;
> +    unsigned long *ns_iopm_ptr, *ns_msrpm_ptr;
> +    unsigned int i;
> +    /* Must be static or hvm_copy_from_guest_phys fails, otherwise. */
> +    static uint8_t ns_iopm[IOPM_SIZE] __attribute__((__aligned__));
> +    static uint8_t ns_msrpm[MSRPM_SIZE] __attribute__((__aligned__));

*boggle*  

Maybe I missed the locking that makes this safe.

Tim.

> +
> +    ns_iopm_ptr = (unsigned long *)ns_iopm;
> +    ns_msrpm_ptr = (unsigned long *)ns_msrpm;
> +
> +    hvm_copy_from_guest_phys(ns_iopm, ns_vmcb->iopm_base_pa, IOPM_SIZE);
> +    hvm_copy_from_guest_phys(ns_msrpm, ns_vmcb->msrpm_base_pa, MSRPM_SIZE);
> +    /* hvm_io_bitmap has type unsigned long, thus
> +     * BYTES_PER_LONG.
> +     */
> +    for (i = 0; i < IOPM_SIZE / BYTES_PER_LONG; i++)
> +        VCPU_NESTEDHVM(v).nh_iopm[i] = hvm_io_bitmap[i] | ns_iopm_ptr[i];
> +
> +    /* v->arch.hvm_svm.msrpm has type unsigned long, thus
> +     * BYTES_PER_LONG.
> +     */
> +    for (i = 0; i < MSRPM_SIZE / BYTES_PER_LONG; i++)
> +        VCPU_NESTEDHVM(v).nh_msrpm[i] = arch_svm->msrpm[i] | ns_msrpm_ptr[i];
> +
> +    host_vmcb->iopm_base_pa =
> +        (uint64_t)virt_to_maddr(VCPU_NESTEDHVM(v).nh_iopm);
> +    host_vmcb->msrpm_base_pa =
> +        (uint64_t)virt_to_maddr(VCPU_NESTEDHVM(v).nh_msrpm);
> +
> +    return 0;
> +}

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

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