The new GNTTABOP_unmap_and_duplicate operation doesn't zero the mapping passed in new_addr, allowing us to perform batch unmaps in p2m code without requiring the use of a multicall.
Signed-off-by: Roger Pau Monné <roger....@citrix.com> Cc: Stefano Stabellini <stefano.stabell...@eu.citrix.com> Cc: Konrad Rzeszutek Wilk <konrad.w...@oracle.com> Cc: David Vrabel <david.vra...@citrix.com> --- Changes since v2: * Rebase on top of 3.12-rc7 Changes since v1: * Append check_duplicate_mfn at the end of remove_page_override. Changes since RFC: * Move shared code between _single and _batch to helper functions. --- I don't currently have a NFS server (the one I had is currently not working due to SD card corruption) and I cannot set up one right now, so I've only tested this with a raw image stored in a local disk. --- arch/x86/include/asm/xen/page.h | 4 +- arch/x86/xen/p2m.c | 132 ++++++++++++++++++++++++++++++----- drivers/xen/grant-table.c | 24 ++---- include/xen/interface/grant_table.h | 22 ++++++ 4 files changed, 146 insertions(+), 36 deletions(-) diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h index b913915..0e101b9 100644 --- a/arch/x86/include/asm/xen/page.h +++ b/arch/x86/include/asm/xen/page.h @@ -51,8 +51,8 @@ extern unsigned long set_phys_range_identity(unsigned long pfn_s, extern int m2p_add_override(unsigned long mfn, struct page *page, struct gnttab_map_grant_ref *kmap_op); -extern int m2p_remove_override(struct page *page, - struct gnttab_map_grant_ref *kmap_op); +extern int m2p_remove_override(struct page **pages, + struct gnttab_map_grant_ref *kmap_ops, int count); extern struct page *m2p_find_override(unsigned long mfn); extern unsigned long m2p_find_override_pfn(unsigned long mfn, unsigned long pfn); diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c index a61c7d5..b1b9b46 100644 --- a/arch/x86/xen/p2m.c +++ b/arch/x86/xen/p2m.c @@ -154,6 +154,8 @@ #include <linux/hash.h> #include <linux/sched.h> #include <linux/seq_file.h> +#include <linux/slab.h> +#include <linux/hardirq.h> #include <asm/cache.h> #include <asm/setup.h> @@ -853,6 +855,7 @@ bool set_phys_to_machine(unsigned long pfn, unsigned long mfn) static RESERVE_BRK_ARRAY(struct list_head, m2p_overrides, M2P_OVERRIDE_HASH); static DEFINE_SPINLOCK(m2p_override_lock); +extern bool gnttab_supports_duplicate; static void __init m2p_override_init(void) { @@ -932,8 +935,8 @@ int m2p_add_override(unsigned long mfn, struct page *page, return 0; } EXPORT_SYMBOL_GPL(m2p_add_override); -int m2p_remove_override(struct page *page, - struct gnttab_map_grant_ref *kmap_op) + +static inline int remove_page_override(struct page *page) { unsigned long flags; unsigned long mfn; @@ -963,6 +966,41 @@ int m2p_remove_override(struct page *page, ClearPagePrivate(page); set_phys_to_machine(pfn, page->index); + + /* + * p2m(m2p(mfn)) == FOREIGN_FRAME(mfn): the mfn is already present + * somewhere in this domain, even before being added to the + * m2p_override (see comment above in m2p_add_override). + * If there are no other entries in the m2p_override corresponding + * to this mfn, then remove the FOREIGN_FRAME_BIT from the p2m for + * the original pfn (the one shared by the frontend): the backend + * cannot do any IO on this page anymore because it has been + * unshared. Removing the FOREIGN_FRAME_BIT from the p2m entry of + * the original pfn causes mfn_to_pfn(mfn) to return the frontend + * pfn again. + */ + mfn &= ~FOREIGN_FRAME_BIT; + pfn = mfn_to_pfn_no_overrides(mfn); + if (get_phys_to_machine(pfn) == FOREIGN_FRAME(mfn) && + m2p_find_override(mfn) == NULL) + set_phys_to_machine(pfn, mfn); + + return 0; +} + +int m2p_remove_override_single(struct page *page, + struct gnttab_map_grant_ref *kmap_op) +{ + unsigned long mfn; + unsigned long pfn; + int ret = 0; + + pfn = page_to_pfn(page); + mfn = get_phys_to_machine(pfn); + ret = remove_page_override(page); + if (ret) + return ret; + if (kmap_op != NULL) { if (!PageHighMem(page)) { struct multicall_space mcs; @@ -1016,24 +1054,82 @@ int m2p_remove_override(struct page *page, } } - /* p2m(m2p(mfn)) == FOREIGN_FRAME(mfn): the mfn is already present - * somewhere in this domain, even before being added to the - * m2p_override (see comment above in m2p_add_override). - * If there are no other entries in the m2p_override corresponding - * to this mfn, then remove the FOREIGN_FRAME_BIT from the p2m for - * the original pfn (the one shared by the frontend): the backend - * cannot do any IO on this page anymore because it has been - * unshared. Removing the FOREIGN_FRAME_BIT from the p2m entry of - * the original pfn causes mfn_to_pfn(mfn) to return the frontend - * pfn again. */ - mfn &= ~FOREIGN_FRAME_BIT; - pfn = mfn_to_pfn_no_overrides(mfn); - if (get_phys_to_machine(pfn) == FOREIGN_FRAME(mfn) && - m2p_find_override(mfn) == NULL) - set_phys_to_machine(pfn, mfn); - return 0; } + +int m2p_remove_override_batch(struct page **pages, + struct gnttab_map_grant_ref *kmap_ops, int count) +{ + struct gnttab_unmap_and_duplicate *unmap_ops = NULL; + int ret = 0, i; + + for (i = 0; i < count; i++) { + ret = remove_page_override(pages[i]); + if (ret) + goto out; + } + + if (kmap_ops != NULL) { + struct page *scratch_page = get_balloon_scratch_page(); + unsigned long scratch_page_address = (unsigned long) + __va(page_to_pfn(scratch_page) << PAGE_SHIFT); + int invcount = 0; + + unmap_ops = kcalloc(count, sizeof(unmap_ops[0]), GFP_KERNEL); + if (!unmap_ops) { + put_balloon_scratch_page(); + ret = -ENOMEM; + goto out; + } + for (i = 0; i < count; i++) { + if (!PageHighMem(pages[i])) { + unmap_ops[invcount].host_addr = kmap_ops[i].host_addr; + unmap_ops[invcount].new_addr = scratch_page_address; + unmap_ops[invcount].handle = kmap_ops[i].handle; + invcount++; + } + } + ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_and_duplicate, unmap_ops, invcount); + if (ret) { + pr_warning("m2p_remove_override_batch: GNTTABOP_unmap_and_duplicate failed"); + put_balloon_scratch_page(); + ret = -1; + goto out; + } + put_balloon_scratch_page(); + } + +out: + kfree(unmap_ops); + return ret; +} + +int m2p_remove_override(struct page **pages, + struct gnttab_map_grant_ref *kmap_ops, int count) +{ + int i, ret; + bool lazy = false; + + if (gnttab_supports_duplicate) { + ret = m2p_remove_override_batch(pages, kmap_ops, count); + if (ret) + return ret; + } else { + if (!in_interrupt() && paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) { + arch_enter_lazy_mmu_mode(); + lazy = true; + } + for (i = 0; i < count; i++) { + ret = m2p_remove_override_single(pages[i], kmap_ops ? + &kmap_ops[i] : NULL); + if (ret) + return ret; + } + if (lazy) + arch_leave_lazy_mmu_mode(); + } + return ret; +} EXPORT_SYMBOL_GPL(m2p_remove_override); struct page *m2p_find_override(unsigned long mfn) diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c index c4d2298..34a4909 100644 --- a/drivers/xen/grant-table.c +++ b/drivers/xen/grant-table.c @@ -66,6 +66,7 @@ static int gnttab_free_count; static grant_ref_t gnttab_free_head; static DEFINE_SPINLOCK(gnttab_list_lock); unsigned long xen_hvm_resume_frames; +bool gnttab_supports_duplicate; EXPORT_SYMBOL_GPL(xen_hvm_resume_frames); static union { @@ -935,8 +936,7 @@ int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops, struct gnttab_map_grant_ref *kmap_ops, struct page **pages, unsigned int count) { - int i, ret; - bool lazy = false; + int ret; ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap_ops, count); if (ret) @@ -945,20 +945,7 @@ int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops, if (xen_feature(XENFEAT_auto_translated_physmap)) return ret; - if (!in_interrupt() && paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) { - arch_enter_lazy_mmu_mode(); - lazy = true; - } - - for (i = 0; i < count; i++) { - ret = m2p_remove_override(pages[i], kmap_ops ? - &kmap_ops[i] : NULL); - if (ret) - return ret; - } - - if (lazy) - arch_leave_lazy_mmu_mode(); + ret = m2p_remove_override(pages, kmap_ops, count); return ret; } @@ -1246,6 +1233,11 @@ int gnttab_init(void) gnttab_free_count = nr_init_grefs - NR_RESERVED_ENTRIES; gnttab_free_head = NR_RESERVED_ENTRIES; + if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_and_duplicate, NULL, 0)) + gnttab_supports_duplicate = false; + else + gnttab_supports_duplicate = true; + printk("Grant table initialized\n"); return 0; diff --git a/include/xen/interface/grant_table.h b/include/xen/interface/grant_table.h index e40fae9..1f49dc1 100644 --- a/include/xen/interface/grant_table.h +++ b/include/xen/interface/grant_table.h @@ -428,6 +428,27 @@ struct gnttab_unmap_and_replace { DEFINE_GUEST_HANDLE_STRUCT(gnttab_unmap_and_replace); /* + * GNTTABOP_unmap_and_duplicate: Destroy one or more grant-reference mappings + * tracked by <handle> but atomically replace the page table entry with one + * pointing to the machine address under <new_addr>. + * NOTES: + * 1. The call may fail in an undefined manner if either mapping is not + * tracked by <handle>. + * 2. After executing a batch of unmaps, it is guaranteed that no stale + * mappings will remain in the device or host TLBs. + */ +#define GNTTABOP_unmap_and_duplicate 12 +struct gnttab_unmap_and_duplicate { + /* IN parameters. */ + uint64_t host_addr; + uint64_t new_addr; + grant_handle_t handle; + /* OUT parameters. */ + int16_t status; /* => enum grant_status */ +}; +DEFINE_GUEST_HANDLE_STRUCT(gnttab_unmap_and_duplicate_t); + +/* * GNTTABOP_set_version: Request a particular version of the grant * table shared table structure. This operation can only be performed * once in any given domain. It must be performed before any grants @@ -522,6 +543,7 @@ DEFINE_GUEST_HANDLE_STRUCT(gnttab_get_version); #define GNTST_bad_copy_arg (-10) /* copy arguments cross page boundary. */ #define GNTST_address_too_big (-11) /* transfer page address too large. */ #define GNTST_eagain (-12) /* Operation not done; try again. */ +#define GNTST_enosys (-13) /* Operation not implemented. */ #define GNTTABOP_error_msgs { \ "okay", \ -- 1.7.7.5 (Apple Git-26) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/