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SubjectRe: [PATCH v6 17/19] xen: introduce XENMEM_pin
On Fri, Sep 27, 2013 at 05:10:05PM +0100, Stefano Stabellini wrote:
> Introduce a new hypercall to pin one or more pages whose machine
> addresses respect a dma_mask passed as an argument
>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> ---
> arch/arm/xen/mm.c | 16 ++++++++++++++++
> arch/x86/xen/mmu.c | 7 +++++++
> include/xen/interface/memory.h | 32 ++++++++++++++++++++++++++++++++
> include/xen/xen-ops.h | 1 +
> 4 files changed, 56 insertions(+), 0 deletions(-)
>
> diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c
> index b305b94..146c1c3 100644
> --- a/arch/arm/xen/mm.c
> +++ b/arch/arm/xen/mm.c
> @@ -55,6 +55,22 @@ static int xen_exchange_memory(xen_ulong_t extents_in,
> return success;
> }
>
> +int xen_pin_page(xen_pfn_t *in_frame, unsigned int address_bits)
> +{
> + struct xen_pin pin = {
> + .in = {
> + .nr_extents = 1,
> + .extent_order = 0,
> + .domid = DOMID_SELF,
> + .address_bits = address_bits
> + },
> + };
> + set_xen_guest_handle(pin.in.extent_start, in_frame);
> +
> + return HYPERVISOR_memory_op(XENMEM_pin, &pin);
> +}
> +EXPORT_SYMBOL_GPL(xen_pin_page);
> +
> int xen_create_contiguous_region(phys_addr_t pstart, unsigned int order,
> unsigned int address_bits,
> dma_addr_t *dma_handle)
> diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
> index 8830883..8f76ce2 100644
> --- a/arch/x86/xen/mmu.c
> +++ b/arch/x86/xen/mmu.c
> @@ -2568,3 +2568,10 @@ int xen_unmap_domain_mfn_range(struct vm_area_struct *vma,
> return -EINVAL;
> }
> EXPORT_SYMBOL_GPL(xen_unmap_domain_mfn_range);
> +
> +int xen_pin_page(xen_pfn_t *in_frame, unsigned int address_bits)
> +{
> + return -ENOSYS;
> +}
> +EXPORT_SYMBOL_GPL(xen_pin_page);
> +
> diff --git a/include/xen/interface/memory.h b/include/xen/interface/memory.h
> index 49db252..66ab578 100644
> --- a/include/xen/interface/memory.h
> +++ b/include/xen/interface/memory.h
> @@ -314,4 +314,36 @@ struct xen_unpin {
> };
> DEFINE_GUEST_HANDLE_STRUCT(xen_unpin);
>
> +/*
> + * XENMEM_pin pins a set of pages to make sure that the hypervisor does
> + * not change the p2m mappings for them.
> + *
> + */
> +#define XENMEM_pin 28
> +struct xen_pin {
> + /*
> + * [IN/OUT] Details of memory extents to be pinned (GMFN bases).
> + * Xen copies back the MFNs corresponding to the GMFNs passed in as
> + * argument.
> + * @in.address_bits contains the maximum number of bits addressable
> + * by the caller. If the machine addresses of the pages to be pinned
> + * are not addressable according to @in.address_bits, the hypercall
> + * fails and returns an errors. The pages are not pinned. Otherwise
^^^^^-error.
What kind of error? And you should probably join the two sentences together
(the "If the ... The pages are not pinned.")


> + * the hypercall succeeds.

and does it return a number of pages that were pinned or just zero?

> + */
> + struct xen_memory_reservation in;
> +
> + /*
> + * [OUT] Number of input extents that were successfully pinned.
> + * 1. The first @nr_pinned input extents were successfully
> + * pinned.
> + * 2. All other input extents are untouched.
> + * 3. If not all input extents are pinned then the return code of this
> + * command will be non-zero.

OK, what return code?

> + */
> + xen_ulong_t nr_pinned;
> +};
> +DEFINE_GUEST_HANDLE_STRUCT(xen_pin);
> +
> +
> #endif /* __XEN_PUBLIC_MEMORY_H__ */
> diff --git a/include/xen/xen-ops.h b/include/xen/xen-ops.h
> index fb2ea8f..4cf4fc5 100644
> --- a/include/xen/xen-ops.h
> +++ b/include/xen/xen-ops.h
> @@ -22,6 +22,7 @@ extern unsigned long *xen_contiguous_bitmap;
> int xen_create_contiguous_region(phys_addr_t pstart, unsigned int order,
> unsigned int address_bits,
> dma_addr_t *dma_handle);
> +int xen_pin_page(xen_pfn_t *in_frame, unsigned int address_bits);
>
> void xen_destroy_contiguous_region(phys_addr_t pstart, unsigned int order);
>
> --
> 1.7.2.5
>


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