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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCHv4 03/14] xen/grant-table: pre-populate kernel unmap ops for xen_gnttab_unmap_refs()
On 26/01/15 18:31, Stefano Stabellini wrote:
> On Mon, 26 Jan 2015, David Vrabel wrote:
>> When unmapping grants, instead of converting the kernel map ops to
>> unmap ops on the fly, pre-populate the set of unmap ops.
>>
>> This allows the grant unmap for the kernel mappings to be trivially
>> batched in the future.
>>
>> Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
>> ---
>> arch/arm/include/asm/xen/page.h | 2 +-
>> arch/arm/xen/p2m.c | 2 +-
>> arch/x86/include/asm/xen/page.h | 2 +-
>> arch/x86/xen/p2m.c | 21 ++++++++++-----------
>> drivers/xen/gntdev.c | 26 ++++++++++++++++++--------
>> drivers/xen/grant-table.c | 4 ++--
>> include/xen/grant_table.h | 2 +-
>> 7 files changed, 34 insertions(+), 25 deletions(-)
>>
>> diff --git a/arch/arm/include/asm/xen/page.h
>> b/arch/arm/include/asm/xen/page.h
>> index 68c739b..2f7e6ff 100644
>> --- a/arch/arm/include/asm/xen/page.h
>> +++ b/arch/arm/include/asm/xen/page.h
>> @@ -92,7 +92,7 @@ extern int set_foreign_p2m_mapping(struct
>> gnttab_map_grant_ref *map_ops,
>> struct page **pages, unsigned int count);
>>
>> extern int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref
>> *unmap_ops,
>> - struct gnttab_map_grant_ref *kmap_ops,
>> + struct gnttab_unmap_grant_ref *kunmap_ops,
>> struct page **pages, unsigned int count);
>>
>> bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn);
>> diff --git a/arch/arm/xen/p2m.c b/arch/arm/xen/p2m.c
>> index 0548577..cb7a14c 100644
>> --- a/arch/arm/xen/p2m.c
>> +++ b/arch/arm/xen/p2m.c
>> @@ -102,7 +102,7 @@ int set_foreign_p2m_mapping(struct gnttab_map_grant_ref
>> *map_ops,
>> 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 gnttab_unmap_grant_ref *kunmap_ops,
>> struct page **pages, unsigned int count)
>> {
>> int i;
>> diff --git a/arch/x86/include/asm/xen/page.h
>> b/arch/x86/include/asm/xen/page.h
>> index 5eea099..e9f52fe 100644
>> --- a/arch/x86/include/asm/xen/page.h
>> +++ b/arch/x86/include/asm/xen/page.h
>> @@ -55,7 +55,7 @@ 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 clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref
>> *unmap_ops,
>> - struct gnttab_map_grant_ref *kmap_ops,
>> + struct gnttab_unmap_grant_ref *kunmap_ops,
>> struct page **pages, unsigned int count);
>> 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 70fb507..df40b28 100644
>> --- a/arch/x86/xen/p2m.c
>> +++ b/arch/x86/xen/p2m.c
>> @@ -816,7 +816,7 @@ static struct page *m2p_find_override(unsigned long mfn)
>> }
>>
>> static int m2p_remove_override(struct page *page,
>> - struct gnttab_map_grant_ref *kmap_op,
>> + struct gnttab_unmap_grant_ref *kunmap_op,
>> unsigned long mfn)
>> {
>> unsigned long flags;
>> @@ -840,7 +840,7 @@ static int m2p_remove_override(struct page *page,
>> list_del(&page->lru);
>> spin_unlock_irqrestore(&m2p_override_lock, flags);
>>
>> - if (kmap_op != NULL) {
>> + if (kunmap_op != NULL) {
>> if (!PageHighMem(page)) {
>> struct multicall_space mcs;
>> struct gnttab_unmap_and_replace *unmap_op;
>> @@ -855,13 +855,13 @@ static int m2p_remove_override(struct page *page,
>> * issued. In this case handle is going to -1 because
>> * it hasn't been modified yet.
>> */
>> - if (kmap_op->handle == -1)
>> + if (kunmap_op->handle == -1)
>> xen_mc_flush();
>> /*
>> * Now if kmap_op->handle is negative it means that the
>> * hypercall actually returned an error.
>> */
>> - if (kmap_op->handle == GNTST_general_error) {
>> + if (kunmap_op->handle == GNTST_general_error) {
>> pr_warn("m2p_remove_override: pfn %lx mfn %lx,
>> failed to modify kernel mappings",
>> pfn, mfn);
>> put_balloon_scratch_page();
>> @@ -873,9 +873,9 @@ static int m2p_remove_override(struct page *page,
>> mcs = __xen_mc_entry(
>> sizeof(struct gnttab_unmap_and_replace));
>> unmap_op = mcs.args;
>> - unmap_op->host_addr = kmap_op->host_addr;
>> + unmap_op->host_addr = kunmap_op->host_addr;
>> unmap_op->new_addr = scratch_page_address;
>> - unmap_op->handle = kmap_op->handle;
>> + unmap_op->handle = kunmap_op->handle;
>>
>> MULTI_grant_table_op(mcs.mc,
>> GNTTABOP_unmap_and_replace, unmap_op, 1);
>> @@ -887,7 +887,6 @@ static int m2p_remove_override(struct page *page,
>>
>> xen_mc_issue(PARAVIRT_LAZY_MMU);
>>
>> - kmap_op->host_addr = 0;
>> put_balloon_scratch_page();
>> }
>> }
>> @@ -912,7 +911,7 @@ static int m2p_remove_override(struct page *page,
>> }
>>
>> int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
>> - struct gnttab_map_grant_ref *kmap_ops,
>> + struct gnttab_unmap_grant_ref *kunmap_ops,
>> struct page **pages, unsigned int count)
>> {
>> int i, ret = 0;
>> @@ -921,7 +920,7 @@ int clear_foreign_p2m_mapping(struct
>> gnttab_unmap_grant_ref *unmap_ops,
>> if (xen_feature(XENFEAT_auto_translated_physmap))
>> return 0;
>>
>> - if (kmap_ops &&
>> + if (kunmap_ops &&
>> !in_interrupt() &&
>> paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {
>> arch_enter_lazy_mmu_mode();
>> @@ -942,8 +941,8 @@ int clear_foreign_p2m_mapping(struct
>> gnttab_unmap_grant_ref *unmap_ops,
>> 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 (kunmap_ops)
>> + ret = m2p_remove_override(pages[i], &kunmap_ops[i],
>> mfn);
>> if (ret)
>> goto out;
>> }
>> diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
>> index 073b4a1..32f6bfe 100644
>> --- a/drivers/xen/gntdev.c
>> +++ b/drivers/xen/gntdev.c
>> @@ -91,6 +91,7 @@ struct grant_map {
>> struct gnttab_map_grant_ref *map_ops;
>> struct gnttab_unmap_grant_ref *unmap_ops;
>> struct gnttab_map_grant_ref *kmap_ops;
>> + struct gnttab_unmap_grant_ref *kunmap_ops;
>> struct page **pages;
>> };
>>
>> @@ -124,6 +125,7 @@ static void gntdev_free_map(struct grant_map *map)
>> kfree(map->map_ops);
>> kfree(map->unmap_ops);
>> kfree(map->kmap_ops);
>> + kfree(map->kunmap_ops);
>> kfree(map);
>> }
>>
>> @@ -140,11 +142,13 @@ static struct grant_map *gntdev_alloc_map(struct
>> gntdev_priv *priv, int count)
>> add->map_ops = kcalloc(count, sizeof(add->map_ops[0]), GFP_KERNEL);
>> add->unmap_ops = kcalloc(count, sizeof(add->unmap_ops[0]), GFP_KERNEL);
>> add->kmap_ops = kcalloc(count, sizeof(add->kmap_ops[0]), GFP_KERNEL);
>> + add->kunmap_ops = kcalloc(count, sizeof(add->kunmap_ops[0]),
>> GFP_KERNEL);
>> add->pages = kcalloc(count, sizeof(add->pages[0]), GFP_KERNEL);
>> if (NULL == add->grants ||
>> NULL == add->map_ops ||
>> NULL == add->unmap_ops ||
>> NULL == add->kmap_ops ||
>> + NULL == add->kunmap_ops ||
>> NULL == add->pages)
>> goto err;
>>
>> @@ -155,6 +159,7 @@ static struct grant_map *gntdev_alloc_map(struct
>> gntdev_priv *priv, int count)
>> add->map_ops[i].handle = -1;
>> add->unmap_ops[i].handle = -1;
>> add->kmap_ops[i].handle = -1;
>> + add->kunmap_ops[i].handle = -1;
>> }
>>
>> add->index = 0;
>> @@ -261,8 +266,6 @@ static int map_grant_pages(struct grant_map *map)
>> gnttab_set_map_op(&map->map_ops[i], addr, map->flags,
>> map->grants[i].ref,
>> map->grants[i].domid);
>> - gnttab_set_unmap_op(&map->unmap_ops[i], addr,
>> - map->flags, -1 /* handle */);
>> }
>> } else {
>> /*
>> @@ -290,13 +293,20 @@ static int map_grant_pages(struct grant_map *map)
>> return err;
>>
>> for (i = 0; i < map->count; i++) {
>> - if (map->map_ops[i].status)
>> + if (map->map_ops[i].status) {
>> err = -EINVAL;
>> - else {
>> - BUG_ON(map->map_ops[i].handle == -1);
>> - map->unmap_ops[i].handle = map->map_ops[i].handle;
>> - pr_debug("map handle=%d\n", map->map_ops[i].handle);
>> + continue;
>> }
>> +
>> + gnttab_set_unmap_op(&map->unmap_ops[i],
>> + map->map_ops[i].host_addr,
>> + map->flags,
>> + map->map_ops[i].handle);
>
> If !use_ptemod (AKA XENFEAT_auto_translated_physmap), we end up calling
> __pa(addr) twice, that is potentially incorrect.
>
> You might be better off avoiding gnttab_set_unmap_op, and open-coding it.
I've fixed this up in what I think is the correct way but my gntdev test
(using gntalloc to allocate some refs for gntdev to map) fails even
without any of these patches in a x86 PVHVM guest.
I suspect gntalloc might not be working right for auto-xlate guests.
David
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