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xen/debug: WARN_ON when identity PFN has no _PAGE_IOMAP flag set.

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Only enabled if XEN_DEBUG is enabled. We print a warning
when:

 pfn_to_mfn(pfn) == pfn, but no VM_IO (_PAGE_IOMAP) flag set
	(and pfn is an identity mapped pfn)
 pfn_to_mfn(pfn) != pfn, and VM_IO flag is set.
	(ditto, pfn is an identity mapped pfn)

[v2: Make it dependent on CONFIG_XEN_DEBUG instead of ..DEBUG_FS]
[v3: Fix compiler warning]

Reviewed-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
Konrad Rzeszutek Wilk 2010-12-23 16:25:29 -05:00
parent 2222e71bd6
commit fc25151d9a
2 changed files with 46 additions and 0 deletions
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8
arch/x86/xen/Kconfig
View File

@ -48,3 +48,11 @@ config XEN_DEBUG_FS
help
Enable statistics output and various tuning options in debugfs.
Enabling this option may incur a significant performance overhead.
config XEN_DEBUG
bool "Enable Xen debug checks"
depends on XEN
default n
help
Enable various WARN_ON checks in the Xen MMU code.
Enabling this option WILL incur a significant performance overhead.

38
arch/x86/xen/mmu.c
View File

@ -547,6 +547,41 @@ pte_t xen_make_pte(pteval_t pte)
}
PV_CALLEE_SAVE_REGS_THUNK(xen_make_pte);
#ifdef CONFIG_XEN_DEBUG
pte_t xen_make_pte_debug(pteval_t pte)
{
phys_addr_t addr = (pte & PTE_PFN_MASK);
phys_addr_t other_addr;
bool io_page = false;
pte_t _pte;
if (pte & _PAGE_IOMAP)
io_page = true;
_pte = xen_make_pte(pte);
if (!addr)
return _pte;
if (io_page &&
(xen_initial_domain() || addr >= ISA_END_ADDRESS)) {
other_addr = pfn_to_mfn(addr >> PAGE_SHIFT) << PAGE_SHIFT;
WARN(addr != other_addr,
"0x%lx is using VM_IO, but it is 0x%lx!\n",
(unsigned long)addr, (unsigned long)other_addr);
} else {
pteval_t iomap_set = (_pte.pte & PTE_FLAGS_MASK) & _PAGE_IOMAP;
other_addr = (_pte.pte & PTE_PFN_MASK);
WARN((addr == other_addr) && (!io_page) && (!iomap_set),
"0x%lx is missing VM_IO (and wasn't fixed)!\n",
(unsigned long)addr);
}
return _pte;
}
PV_CALLEE_SAVE_REGS_THUNK(xen_make_pte_debug);
#endif
pgd_t xen_make_pgd(pgdval_t pgd)
{
pgd = pte_pfn_to_mfn(pgd);
@ -1957,6 +1992,9 @@ __init void xen_ident_map_ISA(void)
static __init void xen_post_allocator_init(void)
{
#ifdef CONFIG_XEN_DEBUG
pv_mmu_ops.make_pte = PV_CALLEE_SAVE(xen_make_pte_debug);
#endif
pv_mmu_ops.set_pte = xen_set_pte;
pv_mmu_ops.set_pmd = xen_set_pmd;
pv_mmu_ops.set_pud = xen_set_pud;