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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH] xc_map_foreign_pages(), a convenient alternative to xc_map_foreign_batch()
xc_map_foreign_batch() can succeed partially. It is awkward to use
when you're only interested in complete success. Provide new
xc_map_foreign_pages() convenience function for that kind of use.
Also convert two obvious calls to use it.
Signed-off-by: Markus Armbruster <armbru@xxxxxxxxxx>
---
The patch converts only those uses of xc_map_foreign_batch() to
xc_map_foreign_pages() where I'm 100% sure it's safe. For the others,
I'd rather have a second opinion from somebody familiar with the code.
Discussion of uses:
* qemu_remap_bucket() in tools/ioemu/vl.c
Tests for mapping failure, although in a slightly sloppy way:
!(pfns[i + --j] & 0xF0000000UL)
This is true when any of the four bits is set. But mapping failed
only when all of them are set, so maybe it should do this instead:
(pfns[i + --j] & 0xF0000000UL) != 0xF0000000UL
* main() in tools/ioemu/vl.c, in __ia64__ code
Doesn't test for mapping failure. Likely candidate for
xc_map_foreign_pages().
* set_vram_mapping() in tools/ioemu/hw/cirrus_vga.c
Doesn't test for mapping failure. Patch converts this one to
xc_map_foreign_pages().
* copy_from_GFW_to_nvram() in tools/libxc/ia64/xc_ia64_hvm_build.c
Doesn't test for mapping failure. Likely candidate for
xc_map_foreign_pages(), but I have no way to test it.
* xc_core_arch_map_p2m() in tools/libxc/xc_core_x86.c
This maps a two level page directory: first a a page of pfns for the
page directory (live_p2m_frame_list_list), using that pages of pfns
for the pages themselves (live_p2m_frame_list), and using that the
actual pages.
Doesn't test for mapping failure. Likely candidate for
xc_map_foreign_pages().
* xc_domain_restore() in tools/libxc/xc_domain_restore.c
Three uses, none of them tests for mapping failure.
I don't understand this code.
The first use of xc_map_foreign_batch() appears to deliberately pass
invalid PFNs.
* map_and_save_p2m_table() in tools/libxc/xc_domain_save.c
Similar to xc_core_arch_map_p2m().
* xc_domain_save() in tools/libxc/xc_domain_save.c
Doesn't test for mapping failure. Likely candidate for
xc_map_foreign_pages().
* xc_domain_resume_any() in tools/libxc/xc_resume.c
Similar to xc_core_arch_map_p2m().
* xenfb_map_fb() in tools/xenfb/xenfb.c
Another map through a two level page directory, roughly similar to
xc_core_arch_map_p2m().
Doesn't test for mapping failure. Patch converts this one to
xc_map_foreign_pages().
diff -r 256160ff19b7 tools/ioemu/hw/cirrus_vga.c
--- a/tools/ioemu/hw/cirrus_vga.c Thu Aug 16 13:27:59 2007 +0100
+++ b/tools/ioemu/hw/cirrus_vga.c Wed Sep 05 17:38:50 2007 +0200
@@ -2561,7 +2561,7 @@ static void *set_vram_mapping(unsigned l
set_mm_mapping(xc_handle, domid, nr_extents, 0, extent_start);
- vram_pointer = xc_map_foreign_batch(xc_handle, domid,
+ vram_pointer = xc_map_foreign_pages(xc_handle, domid,
PROT_READ|PROT_WRITE,
extent_start, nr_extents);
if (vram_pointer == NULL) {
diff -r 256160ff19b7 tools/libxc/xc_misc.c
--- a/tools/libxc/xc_misc.c Thu Aug 16 13:27:59 2007 +0100
+++ b/tools/libxc/xc_misc.c Wed Sep 05 18:31:46 2007 +0200
@@ -224,6 +224,39 @@ int xc_hvm_set_pci_link_route(
unlock_pages(&arg, sizeof(arg));
return rc;
+}
+
+void *xc_map_foreign_pages(int xc_handle, uint32_t dom, int prot,
+ const xen_pfn_t *arr, int num)
+{
+ xen_pfn_t *pfn;
+ void *res;
+ int i;
+
+ pfn = malloc(num * sizeof(*pfn));
+ if (!pfn)
+ return NULL;
+ memcpy(pfn, arr, num * sizeof(*pfn));
+
+ res = xc_map_foreign_batch(xc_handle, dom, prot, pfn, num);
+ if (res) {
+ for (i = 0; i < num; i++) {
+ if ((pfn[i] & 0xF0000000UL) == 0xF0000000UL) {
+ /*
+ * xc_map_foreign_batch() doesn't give us an error
+ * code, so we have to make one up. May not be the
+ * appropriate one.
+ */
+ errno = EINVAL;
+ munmap(res, num * PAGE_SIZE);
+ res = NULL;
+ break;
+ }
+ }
+ }
+
+ free(pfn);
+ return res;
}
/*
diff -r 256160ff19b7 tools/libxc/xenctrl.h
--- a/tools/libxc/xenctrl.h Thu Aug 16 13:27:59 2007 +0100
+++ b/tools/libxc/xenctrl.h Mon Sep 03 09:18:50 2007 +0200
@@ -646,6 +646,14 @@ void *xc_map_foreign_range(int xc_handle
int size, int prot,
unsigned long mfn );
+void *xc_map_foreign_pages(int xc_handle, uint32_t dom, int prot,
+ const xen_pfn_t *arr, int num );
+
+/**
+ * Like xc_map_foreign_pages(), except it can succeeed partially.
+ * When a page cannot be mapped, its PFN in @arr is or'ed with
+ * 0xF0000000 to indicate the error.
+ */
void *xc_map_foreign_batch(int xc_handle, uint32_t dom, int prot,
xen_pfn_t *arr, int num );
diff -r 256160ff19b7 tools/xenfb/xenfb.c
--- a/tools/xenfb/xenfb.c Thu Aug 16 13:27:59 2007 +0100
+++ b/tools/xenfb/xenfb.c Wed Sep 05 17:39:05 2007 +0200
@@ -398,21 +398,15 @@ static int xenfb_map_fb(struct xenfb_pri
if (!pgmfns || !fbmfns)
goto out;
- /*
- * Bug alert: xc_map_foreign_batch() can fail partly and
- * return a non-null value. This is a design flaw. When it
- * happens, we happily continue here, and later crash on
- * access.
- */
xenfb_copy_mfns(mode, n_fbdirs, pgmfns, pd);
- map = xc_map_foreign_batch(xenfb->xc, domid,
+ map = xc_map_foreign_pages(xenfb->xc, domid,
PROT_READ, pgmfns, n_fbdirs);
if (map == NULL)
goto out;
xenfb_copy_mfns(mode, n_fbmfns, fbmfns, map);
munmap(map, n_fbdirs * XC_PAGE_SIZE);
- xenfb->pub.pixels = xc_map_foreign_batch(xenfb->xc, domid,
+ xenfb->pub.pixels = xc_map_foreign_pages(xenfb->xc, domid,
PROT_READ | PROT_WRITE, fbmfns, n_fbmfns);
if (xenfb->pub.pixels == NULL)
goto out;
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