[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v2] xen/x86: add a way to obtain the needed number of memory map entries
Today there is no way for a domain to obtain the number of entries of the machine memory map returned by XENMEM_machine_memory_map hypercall. Modify the interface to return just the needed number of map entries in case the buffer was specified as NULL. Signed-off-by: Juergen Gross <jgross@xxxxxxxx> --- xen/arch/x86/mm.c | 40 +++++++++++++++++++++++++--------------- xen/include/public/memory.h | 2 ++ 2 files changed, 27 insertions(+), 15 deletions(-) diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c index 14552a1..3ff0e97 100644 --- a/xen/arch/x86/mm.c +++ b/xen/arch/x86/mm.c @@ -4736,15 +4736,18 @@ static int _handle_iomem_range(unsigned long s, unsigned long e, XEN_GUEST_HANDLE_PARAM(e820entry_t) buffer_param; XEN_GUEST_HANDLE(e820entry_t) buffer; - if ( ctxt->n + 1 >= ctxt->map.nr_entries ) - return -EINVAL; - ent.addr = (uint64_t)ctxt->s << PAGE_SHIFT; - ent.size = (uint64_t)(s - ctxt->s) << PAGE_SHIFT; - ent.type = E820_RESERVED; - buffer_param = guest_handle_cast(ctxt->map.buffer, e820entry_t); - buffer = guest_handle_from_param(buffer_param, e820entry_t); - if ( __copy_to_guest_offset(buffer, ctxt->n, &ent, 1) ) - return -EFAULT; + if ( !guest_handle_is_null(ctxt->map.buffer) ) + { + if ( ctxt->n + 1 >= ctxt->map.nr_entries ) + return -EINVAL; + ent.addr = (uint64_t)ctxt->s << PAGE_SHIFT; + ent.size = (uint64_t)(s - ctxt->s) << PAGE_SHIFT; + ent.type = E820_RESERVED; + buffer_param = guest_handle_cast(ctxt->map.buffer, e820entry_t); + buffer = guest_handle_from_param(buffer_param, e820entry_t); + if ( __copy_to_guest_offset(buffer, ctxt->n, &ent, 1) ) + return -EFAULT; + } ctxt->n++; } ctxt->s = e + 1; @@ -4978,6 +4981,7 @@ long arch_memory_op(unsigned long cmd, XEN_GUEST_HANDLE_PARAM(void) arg) XEN_GUEST_HANDLE(e820entry_t) buffer; XEN_GUEST_HANDLE_PARAM(e820entry_t) buffer_param; unsigned int i; + bool store; rc = xsm_machine_memory_map(XSM_PRIV); if ( rc ) @@ -4985,12 +4989,15 @@ long arch_memory_op(unsigned long cmd, XEN_GUEST_HANDLE_PARAM(void) arg) if ( copy_from_guest(&ctxt.map, arg, 1) ) return -EFAULT; - if ( ctxt.map.nr_entries < e820.nr_map + 1 ) + + store = !guest_handle_is_null(ctxt.map.buffer); + + if ( store && ctxt.map.nr_entries < e820.nr_map + 1 ) return -EINVAL; buffer_param = guest_handle_cast(ctxt.map.buffer, e820entry_t); buffer = guest_handle_from_param(buffer_param, e820entry_t); - if ( !guest_handle_okay(buffer, ctxt.map.nr_entries) ) + if ( store && !guest_handle_okay(buffer, ctxt.map.nr_entries) ) return -EFAULT; for ( i = 0, ctxt.n = 0, ctxt.s = 0; i < e820.nr_map; ++i, ++ctxt.n ) @@ -5007,10 +5014,13 @@ long arch_memory_op(unsigned long cmd, XEN_GUEST_HANDLE_PARAM(void) arg) if ( rc ) return rc; } - if ( ctxt.map.nr_entries <= ctxt.n + (e820.nr_map - i) ) - return -EINVAL; - if ( __copy_to_guest_offset(buffer, ctxt.n, e820.map + i, 1) ) - return -EFAULT; + if ( store ) + { + if ( ctxt.map.nr_entries <= ctxt.n + (e820.nr_map - i) ) + return -EINVAL; + if ( __copy_to_guest_offset(buffer, ctxt.n, e820.map + i, 1) ) + return -EFAULT; + } ctxt.s = PFN_UP(e820.map[i].addr + e820.map[i].size); } diff --git a/xen/include/public/memory.h b/xen/include/public/memory.h index 5bf840f..e633047 100644 --- a/xen/include/public/memory.h +++ b/xen/include/public/memory.h @@ -339,6 +339,8 @@ DEFINE_XEN_GUEST_HANDLE(xen_memory_map_t); /* * Returns the real physical memory map. Passes the same structure as * XENMEM_memory_map. + * Specifying buffer as NULL will return the number of entries required + * to store the complete memory map. * arg == addr of xen_memory_map_t. */ #define XENMEM_machine_memory_map 10 -- 2.10.2 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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