[PATCH] xen/grant-table: Refactor gnttab_[un]map_refs to avoid m2p_override
Zoltan Kiss
zoltan.kiss at citrix.com
Mon Mar 10 13:14:02 EDT 2014
David/Stefano, can you take a look, and ack if you are happy with this?
I could build it on ARM and a backported version on 3.10 have seen quite
a lot of testing recently.
Zoli
On 27/02/14 15:55, Zoltan Kiss wrote:
> (This is a continuation of "[PATCH v9] xen/grant-table: Avoid m2p_override
> during mapping")
>
> The grant mapping API does m2p_override unnecessarily: only gntdev needs it,
> for blkback and future netback patches it just cause a lock contention, as
> those pages never go to userspace. Therefore this series does the following:
> - the bulk of the original function (everything after the mapping hypercall)
> is moved to arch-dependent set/clear_foreign_p2m_mapping
> - the "if (xen_feature(XENFEAT_auto_translated_physmap))" brach goes to ARM
> - therefore the ARM function could be much smaller, the m2p_override stubs
> could be also removed
> - on x86 the set_phys_to_machine calls were moved up to this new funcion
> from m2p_override functions
> - and m2p_override functions are only called when there is a kmap_ops param
>
> It also removes a stray space from arch/x86/include/asm/xen/page.h.
>
> Signed-off-by: Zoltan Kiss <zoltan.kiss at citrix.com>
> Suggested-by: Anthony Liguori <aliguori at amazon.com>
> Suggested-by: David Vrabel <david.vrabel at citrix.com>
> Suggested-by: Stefano Stabellini <stefano.stabellini at eu.citrix.com>
> ---
> arch/arm/include/asm/xen/page.h | 15 ++---
> arch/arm/xen/p2m.c | 32 +++++++++++
> arch/x86/include/asm/xen/page.h | 11 +++-
> arch/x86/xen/p2m.c | 121 ++++++++++++++++++++++++++++++++++-----
> drivers/xen/grant-table.c | 73 +----------------------
> 5 files changed, 156 insertions(+), 96 deletions(-)
>
> diff --git a/arch/arm/include/asm/xen/page.h b/arch/arm/include/asm/xen/page.h
> index e0965ab..cf4f3e8 100644
> --- a/arch/arm/include/asm/xen/page.h
> +++ b/arch/arm/include/asm/xen/page.h
> @@ -97,16 +97,13 @@ static inline pte_t *lookup_address(unsigned long address, unsigned int *level)
> return NULL;
> }
>
> -static inline int m2p_add_override(unsigned long mfn, struct page *page,
> - struct gnttab_map_grant_ref *kmap_op)
> -{
> - return 0;
> -}
> +extern int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
> + struct gnttab_map_grant_ref *kmap_ops,
> + struct page **pages, unsigned int count);
>
> -static inline int m2p_remove_override(struct page *page, bool clear_pte)
> -{
> - return 0;
> -}
> +extern int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
> + struct gnttab_map_grant_ref *kmap_ops,
> + struct page **pages, unsigned int count);
>
> bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn);
> bool __set_phys_to_machine_multi(unsigned long pfn, unsigned long mfn,
> diff --git a/arch/arm/xen/p2m.c b/arch/arm/xen/p2m.c
> index b31ee1b2..9c48778 100644
> --- a/arch/arm/xen/p2m.c
> +++ b/arch/arm/xen/p2m.c
> @@ -146,6 +146,38 @@ unsigned long __mfn_to_pfn(unsigned long mfn)
> }
> EXPORT_SYMBOL_GPL(__mfn_to_pfn);
>
> +int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
> + struct gnttab_map_grant_ref *kmap_ops,
> + struct page **pages, unsigned int count);
> +{
> + int i;
> +
> + 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);
> + }
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(set_foreign_p2m_mapping);
> +
> +int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
> + struct gnttab_map_grant_ref *kmap_ops,
> + struct page **pages, unsigned int count);
> +{
> + int i;
> +
> + for (i = 0; i < count; i++) {
> + set_phys_to_machine(unmap_ops[i].host_addr >> PAGE_SHIFT,
> + INVALID_P2M_ENTRY);
> + }
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(clear_foreign_p2m_mapping);
> +
> bool __set_phys_to_machine_multi(unsigned long pfn,
> unsigned long mfn, unsigned long nr_pages)
> {
> diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h
> index 3e276eb..c949923 100644
> --- a/arch/x86/include/asm/xen/page.h
> +++ b/arch/x86/include/asm/xen/page.h
> @@ -49,10 +49,17 @@ extern bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn);
> extern unsigned long set_phys_range_identity(unsigned long pfn_s,
> unsigned long pfn_e);
>
> +extern int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
> + struct gnttab_map_grant_ref *kmap_ops,
> + struct page **pages, unsigned int count);
> extern int m2p_add_override(unsigned long mfn, struct page *page,
> struct gnttab_map_grant_ref *kmap_op);
> +extern int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
> + struct gnttab_map_grant_ref *kmap_ops,
> + struct page **pages, unsigned int count);
> extern int m2p_remove_override(struct page *page,
> - struct gnttab_map_grant_ref *kmap_op);
> + struct gnttab_map_grant_ref *kmap_op,
> + unsigned long mfn);
> extern struct page *m2p_find_override(unsigned long mfn);
> extern unsigned long m2p_find_override_pfn(unsigned long mfn, unsigned long pfn);
>
> @@ -121,7 +128,7 @@ static inline unsigned long mfn_to_pfn(unsigned long mfn)
> pfn = m2p_find_override_pfn(mfn, ~0);
> }
>
> - /*
> + /*
> * pfn is ~0 if there are no entries in the m2p for mfn or if the
> * entry doesn't map back to the mfn and m2p_override doesn't have a
> * valid entry for it.
> diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
> index 696c694..85e5d78 100644
> --- a/arch/x86/xen/p2m.c
> +++ b/arch/x86/xen/p2m.c
> @@ -881,6 +881,65 @@ static unsigned long mfn_hash(unsigned long mfn)
> return hash_long(mfn, M2P_OVERRIDE_HASH_SHIFT);
> }
>
> +int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
> + struct gnttab_map_grant_ref *kmap_ops,
> + struct page **pages, unsigned int count)
> +{
> + int i, ret = 0;
> + bool lazy = false;
> + pte_t *pte;
> +
> + if (xen_feature(XENFEAT_auto_translated_physmap))
> + return 0;
> +
> + if (kmap_ops &&
> + !in_interrupt() &&
> + paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {
> + arch_enter_lazy_mmu_mode();
> + lazy = true;
> + }
> +
> + for (i = 0; i < count; i++) {
> + unsigned long mfn, pfn;
> +
> + /* Do not add to override if the map failed. */
> + if (map_ops[i].status)
> + continue;
> +
> + if (map_ops[i].flags & GNTMAP_contains_pte) {
> + pte = (pte_t *) (mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) +
> + (map_ops[i].host_addr & ~PAGE_MASK));
> + mfn = pte_mfn(*pte);
> + } else {
> + mfn = PFN_DOWN(map_ops[i].dev_bus_addr);
> + }
> + pfn = page_to_pfn(pages[i]);
> +
> + WARN_ON(PagePrivate(pages[i]));
> + SetPagePrivate(pages[i]);
> + set_page_private(pages[i], mfn);
> + pages[i]->index = pfn_to_mfn(pfn);
> +
> + if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)))) {
> + ret = -ENOMEM;
> + goto out;
> + }
> +
> + if (kmap_ops) {
> + ret = m2p_add_override(mfn, pages[i], &kmap_ops[i]);
> + if (ret)
> + goto out;
> + }
> + }
> +
> +out:
> + if (lazy)
> + arch_leave_lazy_mmu_mode();
> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(set_foreign_p2m_mapping);
> +
> /* Add an MFN override for a particular page */
> int m2p_add_override(unsigned long mfn, struct page *page,
> struct gnttab_map_grant_ref *kmap_op)
> @@ -899,13 +958,6 @@ int m2p_add_override(unsigned long mfn, struct page *page,
> "m2p_add_override: pfn %lx not mapped", pfn))
> return -EINVAL;
> }
> - WARN_ON(PagePrivate(page));
> - SetPagePrivate(page);
> - set_page_private(page, mfn);
> - page->index = pfn_to_mfn(pfn);
> -
> - if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn))))
> - return -ENOMEM;
>
> if (kmap_op != NULL) {
> if (!PageHighMem(page)) {
> @@ -943,20 +995,62 @@ int m2p_add_override(unsigned long mfn, struct page *page,
> return 0;
> }
> EXPORT_SYMBOL_GPL(m2p_add_override);
> +
> +int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
> + struct gnttab_map_grant_ref *kmap_ops,
> + struct page **pages, unsigned int count)
> +{
> + int i, ret = 0;
> + bool lazy = false;
> +
> + if (xen_feature(XENFEAT_auto_translated_physmap))
> + return 0;
> +
> + if (kmap_ops &&
> + !in_interrupt() &&
> + paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {
> + arch_enter_lazy_mmu_mode();
> + lazy = true;
> + }
> +
> + for (i = 0; i < count; i++) {
> + unsigned long mfn = get_phys_to_machine(page_to_pfn(pages[i]));
> + unsigned long pfn = page_to_pfn(pages[i]);
> +
> + if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT)) {
> + ret = -EINVAL;
> + goto out;
> + }
> +
> + set_page_private(pages[i], INVALID_P2M_ENTRY);
> + WARN_ON(!PagePrivate(pages[i]));
> + ClearPagePrivate(pages[i]);
> + set_phys_to_machine(pfn, pages[i]->index);
> +
> + if (kmap_ops)
> + ret = m2p_remove_override(pages[i], &kmap_ops[i], mfn);
> + if (ret)
> + goto out;
> + }
> +
> +out:
> + if (lazy)
> + arch_leave_lazy_mmu_mode();
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(clear_foreign_p2m_mapping);
> +
> int m2p_remove_override(struct page *page,
> - struct gnttab_map_grant_ref *kmap_op)
> + struct gnttab_map_grant_ref *kmap_op,
> + unsigned long mfn)
> {
> unsigned long flags;
> - unsigned long mfn;
> unsigned long pfn;
> unsigned long uninitialized_var(address);
> unsigned level;
> pte_t *ptep = NULL;
>
> pfn = page_to_pfn(page);
> - mfn = get_phys_to_machine(pfn);
> - if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT))
> - return -EINVAL;
>
> if (!PageHighMem(page)) {
> address = (unsigned long)__va(pfn << PAGE_SHIFT);
> @@ -970,10 +1064,7 @@ int m2p_remove_override(struct page *page,
> spin_lock_irqsave(&m2p_override_lock, flags);
> list_del(&page->lru);
> spin_unlock_irqrestore(&m2p_override_lock, flags);
> - WARN_ON(!PagePrivate(page));
> - ClearPagePrivate(page);
>
> - set_phys_to_machine(pfn, page->index);
> if (kmap_op != NULL) {
> if (!PageHighMem(page)) {
> struct multicall_space mcs;
> diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
> index b84e3ab..6d325bd 100644
> --- a/drivers/xen/grant-table.c
> +++ b/drivers/xen/grant-table.c
> @@ -933,9 +933,6 @@ int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
> struct page **pages, unsigned int count)
> {
> int i, ret;
> - bool lazy = false;
> - pte_t *pte;
> - unsigned long mfn;
>
> ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map_ops, count);
> if (ret)
> @@ -947,45 +944,7 @@ int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
> gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, map_ops + i,
> &map_ops[i].status, __func__);
>
> - /* this is basically a nop on x86 */
> - if (xen_feature(XENFEAT_auto_translated_physmap)) {
> - 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);
> - }
> - 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++) {
> - /* Do not add to override if the map failed. */
> - if (map_ops[i].status)
> - continue;
> -
> - if (map_ops[i].flags & GNTMAP_contains_pte) {
> - pte = (pte_t *) (mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) +
> - (map_ops[i].host_addr & ~PAGE_MASK));
> - mfn = pte_mfn(*pte);
> - } else {
> - mfn = PFN_DOWN(map_ops[i].dev_bus_addr);
> - }
> - ret = m2p_add_override(mfn, pages[i], kmap_ops ?
> - &kmap_ops[i] : NULL);
> - if (ret)
> - goto out;
> - }
> -
> - out:
> - if (lazy)
> - arch_leave_lazy_mmu_mode();
> -
> - return ret;
> + return set_foreign_p2m_mapping(map_ops, kmap_ops, pages, count);
> }
> EXPORT_SYMBOL_GPL(gnttab_map_refs);
>
> @@ -993,39 +952,13 @@ 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)
> return ret;
>
> - /* this is basically a nop on x86 */
> - if (xen_feature(XENFEAT_auto_translated_physmap)) {
> - for (i = 0; i < count; i++) {
> - set_phys_to_machine(unmap_ops[i].host_addr >> PAGE_SHIFT,
> - INVALID_P2M_ENTRY);
> - }
> - 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)
> - goto out;
> - }
> -
> - out:
> - if (lazy)
> - arch_leave_lazy_mmu_mode();
> -
> - return ret;
> + return clear_foreign_p2m_mapping(unmap_ops, kmap_ops, pages, count);
> }
> EXPORT_SYMBOL_GPL(gnttab_unmap_refs);
>
>
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