[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 1 of 2] x86/mm: When mem event automatically promotes access rights, let other subsystems know
xen/arch/x86/hvm/hvm.c | 45 ++++++++++++++++++++++++++++++++++++++------- xen/arch/x86/mm/p2m.c | 8 +++++--- xen/include/asm-x86/p2m.h | 9 +++++---- 3 files changed, 48 insertions(+), 14 deletions(-) The mem event fault handler in the p2m can automatically promote the access rights of a p2m entry. In those scenarios, vcpu's are not paused and they will immediately retry the faulting instructions. This will generate a second fault if the underlying entry type requires so (paging, unsharing, pod, etc). Collapse the two faults into a single one. Signed-off-by: Andres Lagar-Cavilla <andres@xxxxxxxxxxxxxxxx> diff -r 29701f5bdd84 -r d6354df726a0 xen/arch/x86/hvm/hvm.c --- a/xen/arch/x86/hvm/hvm.c +++ b/xen/arch/x86/hvm/hvm.c @@ -1278,9 +1278,13 @@ int hvm_hap_nested_page_fault(unsigned l if ( violation ) { - p2m_mem_access_check(gpa, gla_valid, gla, access_r, access_w, access_x); - rc = 1; - goto out_put_gfn; + if ( !p2m_mem_access_check(gpa, gla_valid, gla, access_r, + access_w, access_x) ) + { + /* Rights not promoted, vcpu paused, work here is done */ + rc = 1; + goto out_put_gfn; + } } } @@ -1288,7 +1292,8 @@ int hvm_hap_nested_page_fault(unsigned l * If this GFN is emulated MMIO or marked as read-only, pass the fault * to the mmio handler. */ - if ( (p2mt == p2m_mmio_dm) || (p2mt == p2m_ram_ro) ) + if ( (p2mt == p2m_mmio_dm) || + (access_w && (p2mt == p2m_ram_ro)) ) { if ( !handle_mmio() ) hvm_inject_exception(TRAP_gp_fault, 0, 0); @@ -1302,7 +1307,7 @@ int hvm_hap_nested_page_fault(unsigned l p2m_mem_paging_populate(v->domain, gfn); /* Mem sharing: unshare the page and try again */ - if ( p2mt == p2m_ram_shared ) + if ( access_w && (p2mt == p2m_ram_shared) ) { ASSERT(!p2m_is_nestedp2m(p2m)); mem_sharing_unshare_page(p2m->domain, gfn, 0); @@ -1319,14 +1324,15 @@ int hvm_hap_nested_page_fault(unsigned l * a large page, we do not change other pages type within that large * page. */ - paging_mark_dirty(v->domain, mfn_x(mfn)); + if ( access_w ) + paging_mark_dirty(v->domain, mfn_x(mfn)); p2m_change_type(v->domain, gfn, p2m_ram_logdirty, p2m_ram_rw); rc = 1; goto out_put_gfn; } /* Shouldn't happen: Maybe the guest was writing to a r/o grant mapping? */ - if ( p2mt == p2m_grant_map_ro ) + if ( access_w && (p2mt == p2m_grant_map_ro) ) { gdprintk(XENLOG_WARNING, "trying to write to read-only grant mapping\n"); @@ -1335,6 +1341,31 @@ int hvm_hap_nested_page_fault(unsigned l goto out_put_gfn; } + if ( access_x && (p2m_is_grant(p2mt)) ) + { + gdprintk(XENLOG_WARNING, + "trying to execut a grant mapping\n"); + hvm_inject_exception(TRAP_gp_fault, 0, 0); + rc = 1; + goto out_put_gfn; + } + + if ( p2m_is_grant(p2mt) ) + { + /* If we haven't caught this by now, then it's a valid access */ + rc = 1; + goto out_put_gfn; + } + + if ( p2mt == p2m_mmio_direct ) + { + if ( !(access_w && + rangeset_contains_singleton(mmio_ro_ranges, mfn_x(mfn))) ) { + rc = 1; + goto out_put_gfn; + } + } + rc = 0; out_put_gfn: put_gfn(p2m->domain, gfn); diff -r 29701f5bdd84 -r d6354df726a0 xen/arch/x86/mm/p2m.c --- a/xen/arch/x86/mm/p2m.c +++ b/xen/arch/x86/mm/p2m.c @@ -1126,7 +1126,7 @@ void p2m_mem_paging_resume(struct domain mem_event_unpause_vcpus(d, &d->mem_paging); } -void p2m_mem_access_check(unsigned long gpa, bool_t gla_valid, unsigned long gla, +int p2m_mem_access_check(unsigned long gpa, bool_t gla_valid, unsigned long gla, bool_t access_r, bool_t access_w, bool_t access_x) { struct vcpu *v = current; @@ -1146,7 +1146,7 @@ void p2m_mem_access_check(unsigned long { p2m->set_entry(p2m, gfn, mfn, PAGE_ORDER_4K, p2mt, p2m_access_rw); p2m_unlock(p2m); - return; + return 1; } p2m_unlock(p2m); @@ -1166,9 +1166,10 @@ void p2m_mem_access_check(unsigned long p2m_lock(p2m); p2m->set_entry(p2m, gfn, mfn, PAGE_ORDER_4K, p2mt, p2m_access_rwx); p2m_unlock(p2m); + return 1; } - return; + return 0; } memset(&req, 0, sizeof(req)); @@ -1192,6 +1193,7 @@ void p2m_mem_access_check(unsigned long (void)mem_event_put_request(d, &d->mem_access, &req); /* VCPU paused */ + return 0; } void p2m_mem_access_resume(struct domain *d) diff -r 29701f5bdd84 -r d6354df726a0 xen/include/asm-x86/p2m.h --- a/xen/include/asm-x86/p2m.h +++ b/xen/include/asm-x86/p2m.h @@ -491,8 +491,9 @@ static inline void p2m_mem_paging_popula #ifdef __x86_64__ /* Send mem event based on the access (gla is -1ull if not available). Handles - * the rw2rx conversion */ -void p2m_mem_access_check(unsigned long gpa, bool_t gla_valid, unsigned long gla, + * the rw2rx conversion. Return value indicate if access rights have been + * promoted with no underlying vcpu pause. */ +int p2m_mem_access_check(unsigned long gpa, bool_t gla_valid, unsigned long gla, bool_t access_r, bool_t access_w, bool_t access_x); /* Resumes the running of the VCPU, restarting the last instruction */ void p2m_mem_access_resume(struct domain *d); @@ -508,10 +509,10 @@ int p2m_get_mem_access(struct domain *d, hvmmem_access_t *access); #else -static inline void p2m_mem_access_check(unsigned long gpa, bool_t gla_valid, +static inline int p2m_mem_access_check(unsigned long gpa, bool_t gla_valid, unsigned long gla, bool_t access_r, bool_t access_w, bool_t access_x) -{ } +{ return 1; } static inline int p2m_set_mem_access(struct domain *d, unsigned long start_pfn, uint32_t nr, hvmmem_access_t access) _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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