Re: [Xen-devel] [PATCH 3/4] libxc: rework vnuma bits in setup_guest

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Tue, May 19, 2015 at 12:23:07PM -0400, Boris Ostrovsky wrote:
> On 05/18/2015 11:34 AM, Wei Liu wrote:
> >Make the setup process similar to PV counterpart. That is, to allocate a
> >P2M array that covers the whole memory range and start from there. This
> >is clearer than using an array with no holes in it.
> >
> >Also the dummy layout should take MMIO hole into consideration. We might
> >end up having two vmemranges in the dummy layout.
> >
> >Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
> >Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
> >Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> >---
> >  tools/libxc/xc_hvm_build_x86.c | 66 
> > ++++++++++++++++++++++++++++++++----------
> >  1 file changed, 50 insertions(+), 16 deletions(-)
> >
> >diff --git a/tools/libxc/xc_hvm_build_x86.c b/tools/libxc/xc_hvm_build_x86.c
> >index df4b7ed..77678f1 100644
> >--- a/tools/libxc/xc_hvm_build_x86.c
> >+++ b/tools/libxc/xc_hvm_build_x86.c
> >@@ -238,6 +238,7 @@ static int setup_guest(xc_interface *xch,
> >  {
> >      xen_pfn_t *page_array = NULL;
> >      unsigned long i, vmemid, nr_pages = args->mem_size >> PAGE_SHIFT;
> >+    unsigned long p2m_size;
> >      unsigned long target_pages = args->mem_target >> PAGE_SHIFT;
> >      unsigned long entry_eip, cur_pages, cur_pfn;
> >      void *hvm_info_page;
> >@@ -254,8 +255,8 @@ static int setup_guest(xc_interface *xch,
> >      xen_pfn_t special_array[NR_SPECIAL_PAGES];
> >      xen_pfn_t ioreq_server_array[NR_IOREQ_SERVER_PAGES];
> >      uint64_t total_pages;
> >-    xen_vmemrange_t dummy_vmemrange;
> >-    unsigned int dummy_vnode_to_pnode;
> >+    xen_vmemrange_t dummy_vmemrange[2];
> >+    unsigned int dummy_vnode_to_pnode[2];
> >      memset(&elf, 0, sizeof(elf));
> >      if ( elf_init(&elf, image, image_size) != 0 )
> >@@ -275,17 +276,37 @@ static int setup_guest(xc_interface *xch,
> >      if ( args->nr_vmemranges == 0 )
> >      {
> >-        /* Build dummy vnode information */
> >-        dummy_vmemrange.start = 0;
> >-        dummy_vmemrange.end   = args->mem_size;
> >-        dummy_vmemrange.flags = 0;
> >-        dummy_vmemrange.nid   = 0;
> >-        args->nr_vmemranges = 1;
> >-        args->vmemranges = &dummy_vmemrange;
> >+        /* Build dummy vnode information
> >+         *
> >+         * Guest physical address space layout:
> >+         * [0, hole_start) [hole_start, 4G) [4G, highmem_end)
> >+         *
> >+         * Of course if there is no high memory, the second vmemrange
> >+         * has no effect on the actual result.
> >+         */
> >-        dummy_vnode_to_pnode = XC_NUMA_NO_NODE;
> >+        dummy_vmemrange[0].start = 0;
> >+        dummy_vmemrange[0].end   = args->lowmem_end;
> >+        dummy_vmemrange[0].flags = 0;
> >+        dummy_vmemrange[0].nid   = 0;
> >+        dummy_vnode_to_pnode[0]  = XC_NUMA_NO_NODE;
> >+        args->nr_vmemranges = 1;
> >          args->nr_vnodes = 1;
> >-        args->vnode_to_pnode = &dummy_vnode_to_pnode;
> >+
> >+        if ( args->highmem_end > (1ULL << 32) )
> >+        {
> >+            dummy_vmemrange[1].start = 1ULL << 32;
> >+            dummy_vmemrange[1].end   = args->highmem_end;
> >+            dummy_vmemrange[1].flags = 0;
> >+            dummy_vmemrange[1].nid   = 0;
> >+            dummy_vnode_to_pnode[1]  = XC_NUMA_NO_NODE;
> >+
> >+            args->nr_vmemranges++;
> >+            args->nr_vnodes++;
> 
> (+Dario)
> 
> Does having high memory mean that we need to have 2 vnodes? We should be

Yes, see the comment above.

> able to cope with multiple vmemranges per node, right?


Yes. That's already done in libxl's function to build hvm vmemranges.

This is only a simple dummy layout so nothing fancy happens here.

Wei.

> 
> -boris
> 
> 
> >+        }
> >+
> >+        args->vmemranges = dummy_vmemrange;
> >+        args->vnode_to_pnode = dummy_vnode_to_pnode;
> >      }
> >

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