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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v4 3/4] xen: implement guest_physmap_(un)pin_range
On Thu, 2013-08-15 at 12:18 +0100, Stefano Stabellini wrote:
> guest_physmap_pin_range pins a range of guest pages so that their p2m
> mappings won't be changed.
> guest_physmap_unpin_range unpins the previously pinned pages.
> The pinning is done using one of the spare bits in the p2m ptes.
>
> Use the newly introduce p2m_walker to implement the two functions on
> ARM.
> Provide empty stubs for x86.
>
>
> Changes in v4:
> - use p2m_walker to implement guest_physmap_pin_range and
> guest_physmap_unpin_range;
> - return -EINVAL when the P2M_DMA_PIN check fails;
> - change the printk into a gdprintk;
> - add a comment on what type of page can be pinned.
>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> ---
> xen/arch/arm/p2m.c | 45
> ++++++++++++++++++++++++++++++++++++++++++++
> xen/include/asm-arm/mm.h | 4 +++
> xen/include/asm-arm/page.h | 7 +++++-
> xen/include/asm-x86/p2m.h | 12 +++++++++++
> 4 files changed, 67 insertions(+), 1 deletions(-)
>
> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> index a77df9a..c185328 100644
> --- a/xen/arch/arm/p2m.c
> +++ b/xen/arch/arm/p2m.c
> @@ -127,6 +127,43 @@ paddr_t p2m_lookup(struct domain *d, paddr_t paddr)
> return p2m.maddr;
> }
>
> +
> +static int _guest_physmap_pin_range(lpae_t *ptep, void *arg)
Single _ namespace is for the compiler. __ is, I think, legal in
"kernel" space but actually this should just be called pin_one_pte or
something like that.
> +{
> + lpae_t pte = *ptep;
> + if ( pte.p2m.avail & P2M_DMA_PIN )
> + return -EINVAL;
> + pte.p2m.avail |= P2M_DMA_PIN;
I think test_and_set_bit would be better here and you should operate on
ptep directly IMHO rather than changing a copy and writing that. Might
require a pte_modified macro with the flushing stuff from write_pte.
> + write_pte(ptep, pte);
> + return 0;
> +}
> +
> +int guest_physmap_pin_range(struct domain *d,
> + xen_pfn_t gpfn,
> + unsigned int order)
> +{
> + return p2m_walker(d, gpfn << PAGE_SHIFT, order,
> + _guest_physmap_pin_range, NULL);
> +}
> +
> +static int _guest_physmap_unpin_range(lpae_t *ptep, void *arg)
unpin_on_pte or something.
> +{
> + lpae_t pte = *ptep;
> + if ( !pte.p2m.avail & P2M_DMA_PIN )
> + return -EINVAL;
> + pte.p2m.avail &= ~P2M_DMA_PIN;
> + write_pte(ptep, pte);
> + return 0;
> +}
> +
> +int guest_physmap_unpin_range(struct domain *d,
> + xen_pfn_t gpfn,
> + unsigned int order)
> +{
> + return p2m_walker(d, gpfn << PAGE_SHIFT, order,
> + _guest_physmap_unpin_range, NULL);
> +}
> +
> int guest_physmap_mark_populate_on_demand(struct domain *d,
> unsigned long gfn,
> unsigned int order)
> @@ -236,6 +273,14 @@ static int create_p2m_entries(struct domain *d,
> cur_second_offset = second_table_offset(addr);
> }
>
> + if ( third[third_table_offset(addr)].p2m.avail & P2M_DMA_PIN )
test_bit.
> + {
> + rc = -EINVAL;
> + gdprintk(XENLOG_WARNING, "cannot change p2m mapping for
> paddr=%"PRIpaddr
> + " domid=%d, the page is pinned\n", addr, d->domain_id);
> + goto out;
> + }
> +
> flush = third[third_table_offset(addr)].p2m.valid;
>
> /* Allocate a new RAM page and attach */
> diff --git a/xen/include/asm-arm/mm.h b/xen/include/asm-arm/mm.h
> index df6fea9..34167e6 100644
> --- a/xen/include/asm-arm/mm.h
> +++ b/xen/include/asm-arm/mm.h
> @@ -317,6 +317,10 @@ void free_init_memory(void);
>
> int guest_physmap_mark_populate_on_demand(struct domain *d, unsigned long
> gfn,
> unsigned int order);
> +int guest_physmap_pin_range(struct domain *d, xen_pfn_t gpfn,
> + unsigned int order);
> +int guest_physmap_unpin_range(struct domain *d, xen_pfn_t gpfn,
> + unsigned int order);
>
> extern void put_page_type(struct page_info *page);
> static inline void put_page_and_type(struct page_info *page)
> diff --git a/xen/include/asm-arm/page.h b/xen/include/asm-arm/page.h
> index 41e9eff..c08cfca 100644
> --- a/xen/include/asm-arm/page.h
> +++ b/xen/include/asm-arm/page.h
> @@ -153,11 +153,16 @@ typedef struct {
> unsigned long hint:1; /* In a block of 16 contiguous entries */
> unsigned long sbz2:1;
> unsigned long xn:1; /* eXecute-Never */
> - unsigned long avail:4; /* Ignored by hardware */
> + unsigned long avail:4; /* Ignored by hardware, see below */
>
> unsigned long sbz1:5;
> } __attribute__((__packed__)) lpae_p2m_t;
>
> +/* Xen "avail" bits allocation in third level entries */
> +#define P2M_DMA_PIN (1<<0) /* The page has been "pinned": the hypervisor
> + promises not to change the p2m mapping.
> + Only normal r/w guest RAM can be pinned.
> */
> +
> /*
> * Walk is the common bits of p2m and pt entries which are needed to
> * simply walk the table (e.g. for debug).
> diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
> index 43583b2..b08a722 100644
> --- a/xen/include/asm-x86/p2m.h
> +++ b/xen/include/asm-x86/p2m.h
> @@ -492,6 +492,18 @@ void guest_physmap_remove_page(struct domain *d,
> /* Set a p2m range as populate-on-demand */
> int guest_physmap_mark_populate_on_demand(struct domain *d, unsigned long
> gfn,
> unsigned int order);
> +static inline int guest_physmap_pin_range(struct domain *d,
> + xen_pfn_t gpfn,
> + unsigned int order)
> +{
> + return -ENOSYS;
> +}
> +static inline int guest_physmap_unpin_range(struct domain *d,
> + xen_pfn_t gpfn,
> + unsigned int order)
> +{
> + return -ENOSYS;
> +}
>
> /* Change types across all p2m entries in a domain */
> void p2m_change_entry_type_global(struct domain *d,
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