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SubjectRe: [PATCH v2 14/20] xen/grant-table: Make it running on 64KB granularity
On Thu, 9 Jul 2015, Julien Grall wrote:
> The Xen interface is using 4KB page granularity. This means that each
> grant is 4KB.
>
> The current implementation allocates a Linux page per grant. On Linux
> using 64KB page granularity, only the first 4KB of the page will be
> used.
>
> We could decrease the memory wasted by sharing the page with multiple
> grant. It will require some care with the {Set,Clear}ForeignPage macro.
>
> Note that no changes has been made in the x86 code because both Linux
> and Xen will only use 4KB page granularity.
>
> Signed-off-by: Julien Grall <julien.grall@citrix.com>
> Reviewed-by: David Vrabel <david.vrabel@citrix.com>
> Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> Cc: Russell King <linux@arm.linux.org.uk>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> ---
> Changes in v2
> - Add David's reviewed-by
> ---
> arch/arm/xen/p2m.c | 6 +++---
> drivers/xen/grant-table.c | 6 +++---
> 2 files changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/arch/arm/xen/p2m.c b/arch/arm/xen/p2m.c
> index 887596c..0ed01f2 100644
> --- a/arch/arm/xen/p2m.c
> +++ b/arch/arm/xen/p2m.c
> @@ -93,8 +93,8 @@ int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
> for (i = 0; i < count; i++) {
> if (map_ops[i].status)
> continue;
> - set_phys_to_machine(map_ops[i].host_addr >> PAGE_SHIFT,
> - map_ops[i].dev_bus_addr >> PAGE_SHIFT);
> + set_phys_to_machine(map_ops[i].host_addr >> XEN_PAGE_SHIFT,
> + map_ops[i].dev_bus_addr >> XEN_PAGE_SHIFT);
> }
>
> return 0;
> @@ -108,7 +108,7 @@ int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
> int i;
>
> for (i = 0; i < count; i++) {
> - set_phys_to_machine(unmap_ops[i].host_addr >> PAGE_SHIFT,
> + set_phys_to_machine(unmap_ops[i].host_addr >> XEN_PAGE_SHIFT,
> INVALID_P2M_ENTRY);
> }
>
> diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
> index 3679293..0a1f903 100644
> --- a/drivers/xen/grant-table.c
> +++ b/drivers/xen/grant-table.c

The arm part is fine, but aren't you missing the change to RPP and SPP?


> @@ -668,7 +668,7 @@ int gnttab_setup_auto_xlat_frames(phys_addr_t addr)
> if (xen_auto_xlat_grant_frames.count)
> return -EINVAL;
>
> - vaddr = xen_remap(addr, PAGE_SIZE * max_nr_gframes);
> + vaddr = xen_remap(addr, XEN_PAGE_SIZE * max_nr_gframes);
> if (vaddr == NULL) {
> pr_warn("Failed to ioremap gnttab share frames (addr=%pa)!\n",
> &addr);
> @@ -680,7 +680,7 @@ int gnttab_setup_auto_xlat_frames(phys_addr_t addr)
> return -ENOMEM;
> }
> for (i = 0; i < max_nr_gframes; i++)
> - pfn[i] = PFN_DOWN(addr) + i;
> + pfn[i] = XEN_PFN_DOWN(addr) + i;
>
> xen_auto_xlat_grant_frames.vaddr = vaddr;
> xen_auto_xlat_grant_frames.pfn = pfn;
> @@ -1004,7 +1004,7 @@ static void gnttab_request_version(void)
> {
> /* Only version 1 is used, which will always be available. */
> grant_table_version = 1;
> - grefs_per_grant_frame = PAGE_SIZE / sizeof(struct grant_entry_v1);
> + grefs_per_grant_frame = XEN_PAGE_SIZE / sizeof(struct grant_entry_v1);
> gnttab_interface = &gnttab_v1_ops;
>
> pr_info("Grant tables using version %d layout\n", grant_table_version);
> --
> 2.1.4
>


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