From 45c141269c81c46836bd065bf0da15cad2881011 Mon Sep 17 00:00:00 2001 From: George Dunlap Date: Wed, 10 Apr 2019 16:43:30 +0100 Subject: [PATCH] altp2m: Add a function to automatically handle copying / prepopulating from hostpm Signed-off-by: George Dunlap --- xen/arch/x86/mm/mem_access.c | 65 +++++++++++++++++++++++++----------- xen/arch/x86/mm/p2m.c | 38 ++++----------------- 2 files changed, 52 insertions(+), 51 deletions(-) diff --git a/xen/arch/x86/mm/mem_access.c b/xen/arch/x86/mm/mem_access.c index a144bb0ce4..253ec94d1b 100644 --- a/xen/arch/x86/mm/mem_access.c +++ b/xen/arch/x86/mm/mem_access.c @@ -255,43 +255,70 @@ bool p2m_mem_access_check(paddr_t gpa, unsigned long gla, return (p2ma != p2m_access_n2rwx); } -int p2m_set_altp2m_mem_access(struct domain *d, struct p2m_domain *hp2m, - struct p2m_domain *ap2m, p2m_access_t a, - gfn_t gfn) +static int get_altp2m_entry(struct p2m_domain *ap2m, + gfn_t gfn, mfn_t *mfn, p2m_type_t *t, + p2m_access_t *a, bool prepopulate) { - mfn_t mfn; - p2m_type_t t; - p2m_access_t old_a; - unsigned int page_order; - unsigned long gfn_l = gfn_x(gfn); - int rc; - - mfn = ap2m->get_entry(ap2m, gfn, &t, &old_a, 0, NULL, NULL); + *mfn = ap2m->get_entry(ap2m, gfn, t, a, 0, NULL, NULL); /* Check host p2m if no valid entry in alternate */ - if ( !mfn_valid(mfn) ) + if ( !mfn_valid(*mfn) ) { + struct p2m_domain *hp2m = p2m_get_hostp2m(ap2m->domain); + unsigned int page_order; + int rc; - mfn = __get_gfn_type_access(hp2m, gfn_l, &t, &old_a, - P2M_ALLOC | P2M_UNSHARE, &page_order, 0); + *mfn = __get_gfn_type_access(hp2m, gfn, t, old_a, + P2M_ALLOC | P2M_UNSHARE, &page_order, 0); rc = -ESRCH; - if ( !mfn_valid(mfn) || t != p2m_ram_rw ) + if ( !mfn_valid(*mfn) || *t != p2m_ram_rw ) return rc; /* If this is a superpage, copy that first */ - if ( page_order != PAGE_ORDER_4K ) + if ( prepopulate && page_order != PAGE_ORDER_4K ) { unsigned long mask = ~((1UL << page_order) - 1); - gfn_t gfn2 = _gfn(gfn_l & mask); - mfn_t mfn2 = _mfn(mfn_x(mfn) & mask); + gfn_t gfn_aligned = _gfn(gfn & mask); + mfn_t mfn_aligned = _mfn(mfn_x(mfn) & mask); - rc = ap2m->set_entry(ap2m, gfn2, mfn2, page_order, t, old_a, 1); + rc = ap2m->set_entry(ap2m, gfn_aligned, mfn_aligned, page_order, t, old_a, 1); if ( rc ) return rc; } } + return 0; +} + +int altp2m_get_entry_seethrough(struct p2m_domain *ap2m, + gfn_t gfn, mfn_t *mfn, p2m_type_t *t, + p2m_access_t *a) +{ + return get_altp2m_entry(ap2m, gfn, mfn, t, a, false); +} + +int altp2m_get_entry_prepopulate(struct p2m_domain *ap2m, + gfn_t gfn, mfn_t *mfn, p2m_type_t *t, + p2m_access_t *a) +{ + return get_altp2m_entry(ap2m, gfn, mfn, t, a, true); +} + +int p2m_set_altp2m_mem_access(struct domain *d, struct p2m_domain *hp2m, + struct p2m_domain *ap2m, p2m_access_t a, + gfn_t gfn) +{ + mfn_t mfn; + p2m_type_t t; + p2m_access_t old_a; + unsigned long gfn_l = gfn_x(gfn); + int rc; + + rc = alt2m_get_entry_prepopulate(ap2m, gfn, &mfn, &t, &old_a); + if ( rc ) + return rc; + /* * Inherit the old suppress #VE bit value if it is already set, or set it * to 1 otherwise diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c index b9bbb8f485..d9f7135be5 100644 --- a/xen/arch/x86/mm/p2m.c +++ b/xen/arch/x86/mm/p2m.c @@ -2636,47 +2636,21 @@ int p2m_change_altp2m_gfn(struct domain *d, unsigned int idx, p2m_lock(hp2m); p2m_lock(ap2m); - mfn = ap2m->get_entry(ap2m, old_gfn, &t, &a, 0, NULL, NULL); - if ( gfn_eq(new_gfn, INVALID_GFN) ) { + mfn = ap2m->get_entry(ap2m, old_gfn, &t, &a, 0, NULL, NULL); if ( mfn_valid(mfn) ) p2m_remove_page(ap2m, gfn_x(old_gfn), mfn_x(mfn), PAGE_ORDER_4K); rc = 0; goto out; } - /* Check host p2m if no valid entry in alternate */ - if ( !mfn_valid(mfn) ) - { - mfn = __get_gfn_type_access(hp2m, gfn_x(old_gfn), &t, &a, - P2M_ALLOC, &page_order, 0); - - if ( !mfn_valid(mfn) || t != p2m_ram_rw ) - goto out; - - /* If this is a superpage, copy that first */ - if ( page_order != PAGE_ORDER_4K ) - { - gfn_t gfn; - unsigned long mask; - - mask = ~((1UL << page_order) - 1); - gfn = _gfn(gfn_x(old_gfn) & mask); - mfn = _mfn(mfn_x(mfn) & mask); - - if ( ap2m->set_entry(ap2m, gfn, mfn, page_order, t, a, 1) ) - goto out; - } - } - - mfn = ap2m->get_entry(ap2m, new_gfn, &t, &a, 0, NULL, NULL); - - if ( !mfn_valid(mfn) ) - mfn = hp2m->get_entry(hp2m, new_gfn, &t, &a, 0, NULL, NULL); + rc = altp2m_get_entry_prepopulate(ap2m, old_gfn, &mfn, &t, &a); + if ( rc ) + goto out; - /* Note: currently it is not safe to remap to a shared entry */ - if ( !mfn_valid(mfn) || (t != p2m_ram_rw) ) + rc = altp2m_get_entry_seethrough(ap2m, new_gfn, &mfn, &t, &a); + if ( rc ) goto out; if ( !ap2m->set_entry(ap2m, old_gfn, mfn, PAGE_ORDER_4K, t, a, -- 2.20.1