[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v11 5/7] memory: add check_get_page_from_gfn() as a wrapper...
...for some uses of get_page_from_gfn(). There are many occurrences of the following pattern in the code: q = <readonly look-up> ? P2M_ALLOC : P2M_UNSHARE; page = get_page_from_gfn(d, gfn, &p2mt, q); if ( p2m_is_paging(p2mt) ) { if ( page ) put_page(page); p2m_mem_paging_populate(d, gfn); return <-EAGAIN or equivalent>; } if ( (q & P2M_UNSHARE) && p2m_is_shared(p2mt) ) { if ( page ) put_page(page); return <-EAGAIN or equivalent>; } if ( !page ) return <-EINVAL or equivalent>; There are some small differences between the exact way the occurrences are coded but the desired semantic is the same. This patch introduces a new common implementation of this code in check_get_page_from_gfn() and then converts the various open-coded patterns into calls to this new function. Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx> Reviewed-by: Roger Pau Monne <roger.pau@xxxxxxxxxx> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx> --- Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> Cc: George Dunlap <George.Dunlap@xxxxxxxxxxxxx> Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx> Cc: Julien Grall <julien.grall@xxxxxxx> Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx> Cc: Tim Deegan <tim@xxxxxxx> Cc: Wei Liu <wei.liu2@xxxxxxxxxx> v11: - Forward declare p2m_type_t in p2m-common.h to allow the duplicate declarations of check_get_page_from_gfn() to be removed, and hence add Jan's R-b. v10: - Expand commit comment to point out the reason for the duplicate declarations of check_get_page_from_gfn(). v9: - Defer P2M type checks (beyond shared or paging) to the caller. v7: - Fix ARM build by introducing p2m_is_readonly() predicate. - Re-name get_paged_frame() -> check_get_page_from_gfn(). - Adjust default cases of callers switch-ing on return value. v3: - Addressed comments from George. v2: - New in v2. --- xen/arch/x86/hvm/emulate.c | 25 +++++++++++----------- xen/arch/x86/hvm/hvm.c | 14 +------------ xen/common/grant_table.c | 32 ++++++++++++++--------------- xen/common/memory.c | 49 +++++++++++++++++++++++++++++++++++--------- xen/include/asm-arm/p2m.h | 4 ++-- xen/include/asm-x86/p2m.h | 5 ++--- xen/include/xen/p2m-common.h | 6 ++++++ 7 files changed, 77 insertions(+), 58 deletions(-) diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c index a577685dc6..480840b202 100644 --- a/xen/arch/x86/hvm/emulate.c +++ b/xen/arch/x86/hvm/emulate.c @@ -356,22 +356,21 @@ static int hvmemul_acquire_page(unsigned long gmfn, struct page_info **page) struct domain *curr_d = current->domain; p2m_type_t p2mt; - *page = get_page_from_gfn(curr_d, gmfn, &p2mt, P2M_UNSHARE); - - if ( *page == NULL ) - return X86EMUL_UNHANDLEABLE; - - if ( p2m_is_paging(p2mt) ) + switch ( check_get_page_from_gfn(curr_d, _gfn(gmfn), false, &p2mt, + page) ) { - put_page(*page); - p2m_mem_paging_populate(curr_d, gmfn); - return X86EMUL_RETRY; - } + case 0: + break; - if ( p2m_is_shared(p2mt) ) - { - put_page(*page); + case -EAGAIN: return X86EMUL_RETRY; + + default: + ASSERT_UNREACHABLE(); + /* Fallthrough */ + + case -EINVAL: + return X86EMUL_UNHANDLEABLE; } /* This code should not be reached if the gmfn is not RAM */ diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c index fe6c9c592f..6bb1da07eb 100644 --- a/xen/arch/x86/hvm/hvm.c +++ b/xen/arch/x86/hvm/hvm.c @@ -2536,20 +2536,8 @@ static void *_hvm_map_guest_frame(unsigned long gfn, bool_t permanent, struct page_info *page; struct domain *d = current->domain; - page = get_page_from_gfn(d, gfn, &p2mt, - writable ? P2M_UNSHARE : P2M_ALLOC); - if ( (p2m_is_shared(p2mt) && writable) || !page ) - { - if ( page ) - put_page(page); - return NULL; - } - if ( p2m_is_paging(p2mt) ) - { - put_page(page); - p2m_mem_paging_populate(d, gfn); + if ( check_get_page_from_gfn(d, _gfn(gfn), !writable, &p2mt, &page) ) return NULL; - } if ( writable ) { diff --git a/xen/common/grant_table.c b/xen/common/grant_table.c index 0f0b7b1a49..3604a8812c 100644 --- a/xen/common/grant_table.c +++ b/xen/common/grant_table.c @@ -374,25 +374,23 @@ static int get_paged_frame(unsigned long gfn, mfn_t *mfn, struct page_info **page, bool readonly, struct domain *rd) { - int rc = GNTST_okay; p2m_type_t p2mt; + int rc; - *mfn = INVALID_MFN; - *page = get_page_from_gfn(rd, gfn, &p2mt, - readonly ? P2M_ALLOC : P2M_UNSHARE); - if ( !*page ) + rc = check_get_page_from_gfn(rd, _gfn(gfn), readonly, &p2mt, page); + switch ( rc ) { -#ifdef P2M_SHARED_TYPES - if ( p2m_is_shared(p2mt) ) - return GNTST_eagain; -#endif -#ifdef P2M_PAGES_TYPES - if ( p2m_is_paging(p2mt) ) - { - p2m_mem_paging_populate(rd, gfn); - return GNTST_eagain; - } -#endif + case 0: + break; + + case -EAGAIN: + return GNTST_eagain; + + default: + ASSERT_UNREACHABLE(); + /* Fallthrough */ + + case -EINVAL: return GNTST_bad_page; } @@ -406,7 +404,7 @@ static int get_paged_frame(unsigned long gfn, mfn_t *mfn, *mfn = page_to_mfn(*page); - return rc; + return GNTST_okay; } static inline void diff --git a/xen/common/memory.c b/xen/common/memory.c index 85611ddae4..9b592d4f66 100644 --- a/xen/common/memory.c +++ b/xen/common/memory.c @@ -1625,37 +1625,66 @@ void destroy_ring_for_helper( } } -int prepare_ring_for_helper( - struct domain *d, unsigned long gmfn, struct page_info **_page, - void **_va) +/* + * Acquire a pointer to struct page_info for a specified doman and GFN, + * checking whether the page has been paged out, or needs unsharing. + * If the function succeeds then zero is returned, page_p is written + * with a pointer to the struct page_info with a reference taken, and + * p2mt_p it is written with the P2M type of the page. The caller is + * responsible for dropping the reference. + * If the function fails then an appropriate errno is returned and the + * values referenced by page_p and p2mt_p are undefined. + */ +int check_get_page_from_gfn(struct domain *d, gfn_t gfn, bool readonly, + p2m_type_t *p2mt_p, struct page_info **page_p) { - struct page_info *page; + p2m_query_t q = readonly ? P2M_ALLOC : P2M_UNSHARE; p2m_type_t p2mt; - void *va; + struct page_info *page; - page = get_page_from_gfn(d, gmfn, &p2mt, P2M_UNSHARE); + page = get_page_from_gfn(d, gfn_x(gfn), &p2mt, q); #ifdef CONFIG_HAS_MEM_PAGING if ( p2m_is_paging(p2mt) ) { if ( page ) put_page(page); - p2m_mem_paging_populate(d, gmfn); - return -ENOENT; + + p2m_mem_paging_populate(d, gfn_x(gfn)); + return -EAGAIN; } #endif #ifdef CONFIG_HAS_MEM_SHARING - if ( p2m_is_shared(p2mt) ) + if ( (q & P2M_UNSHARE) && p2m_is_shared(p2mt) ) { if ( page ) put_page(page); - return -ENOENT; + + return -EAGAIN; } #endif if ( !page ) return -EINVAL; + *p2mt_p = p2mt; + *page_p = page; + return 0; +} + +int prepare_ring_for_helper( + struct domain *d, unsigned long gmfn, struct page_info **_page, + void **_va) +{ + p2m_type_t p2mt; + struct page_info *page; + void *va; + int rc; + + rc = check_get_page_from_gfn(d, _gfn(gmfn), false, &p2mt, &page); + if ( rc ) + return (rc == -EAGAIN) ? -ENOENT : rc; + if ( !get_page_type(page, PGT_writable_page) ) { put_page(page); diff --git a/xen/include/asm-arm/p2m.h b/xen/include/asm-arm/p2m.h index 8823707c17..c03557544a 100644 --- a/xen/include/asm-arm/p2m.h +++ b/xen/include/asm-arm/p2m.h @@ -110,7 +110,7 @@ struct p2m_domain { * future, it's possible to use higher value for pseudo-type and don't store * them in the p2m entry. */ -typedef enum { +enum p2m_type { p2m_invalid = 0, /* Nothing mapped here */ p2m_ram_rw, /* Normal read/write guest RAM */ p2m_ram_ro, /* Read-only; writes are silently dropped */ @@ -124,7 +124,7 @@ typedef enum { p2m_iommu_map_rw, /* Read/write iommu mapping */ p2m_iommu_map_ro, /* Read-only iommu mapping */ p2m_max_real_type, /* Types after this won't be store in the p2m */ -} p2m_type_t; +}; /* We use bitmaps and mask to handle groups of types */ #define p2m_to_mask(_t) (1UL << (_t)) diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h index d4b3cfcb6e..b97f13a2a5 100644 --- a/xen/include/asm-x86/p2m.h +++ b/xen/include/asm-x86/p2m.h @@ -52,7 +52,7 @@ extern bool_t opt_hap_1gb, opt_hap_2mb; * cannot be non-zero, otherwise, hardware generates io page faults when * device access those pages. Therefore, p2m_ram_rw has to be defined as 0. */ -typedef enum { +enum p2m_type { p2m_ram_rw = 0, /* Normal read/write guest RAM */ p2m_invalid = 1, /* Nothing mapped here */ p2m_ram_logdirty = 2, /* Temporarily read-only for log-dirty */ @@ -72,7 +72,7 @@ typedef enum { p2m_ram_broken = 13, /* Broken page, access cause domain crash */ p2m_map_foreign = 14, /* ram pages from foreign domain */ p2m_ioreq_server = 15, -} p2m_type_t; +}; /* Modifiers to the query */ typedef unsigned int p2m_query_t; @@ -492,7 +492,6 @@ static inline struct page_info *get_page_from_gfn( return mfn_valid(_mfn(gfn)) && get_page(page, d) ? page : NULL; } - /* General conversion function from mfn to gfn */ static inline unsigned long mfn_to_gfn(struct domain *d, mfn_t mfn) { diff --git a/xen/include/xen/p2m-common.h b/xen/include/xen/p2m-common.h index 74311950ad..f4d30efe5f 100644 --- a/xen/include/xen/p2m-common.h +++ b/xen/include/xen/p2m-common.h @@ -32,5 +32,11 @@ unsigned long p2m_pod_decrease_reservation(struct domain *d, gfn_t gfn, unsigned int order); +typedef enum p2m_type p2m_type_t; + +int __must_check check_get_page_from_gfn(struct domain *d, gfn_t gfn, + bool readonly, p2m_type_t *p2mt_p, + struct page_info **page_p); + #endif /* _XEN_P2M_COMMON_H */ -- 2.11.0 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
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