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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 2/2] x86/xen: make mfn_to_pfn() work with MFNs that are 1:1 in the p2m
From: David Vrabel <david.vrabel@xxxxxxxxxx>
The _PAGE_IOMAP PTE flag is used to indicate that the PTE contains an
MFN that is an identify frame (1:1) in the p2m. This is so the
correct conversion of MFN to PFN can be done reading a PTE.
If mfn_to_pfn() returned the correct PFN instead the _PAGE_IOMAP flag
is not required and can be removed.
In mfn_to_pfn() the PFN found in the M2P is checked in P2M. If the
two MFNs differ then the MFN is one of three possibilities:
a) its a foreign MFN with an m2p override.
b) it's a foreign MFN with /no/ m2p override.
c) it's a identity MFN.
It is not permitted to call mfn_to_pfn() no a foreign MFN without an
override was the resulting PFN will not incorrect. We can therefore
assume case (c) and return PFN == MFN.
[ This patch should probably be split into the Xen-specific parts and
an x86 patch to remove _PAGE_IOMAP. ]
Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
---
arch/x86/include/asm/pgtable_types.h | 12 +++---
arch/x86/include/asm/xen/page.h | 18 +++++++---
arch/x86/mm/init_32.c | 2 +-
arch/x86/mm/init_64.c | 2 +-
arch/x86/pci/i386.c | 2 -
arch/x86/xen/enlighten.c | 2 -
arch/x86/xen/mmu.c | 58 +++++-----------------------------
7 files changed, 28 insertions(+), 68 deletions(-)
diff --git a/arch/x86/include/asm/pgtable_types.h
b/arch/x86/include/asm/pgtable_types.h
index 0ecac25..0b12657 100644
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -17,7 +17,7 @@
#define _PAGE_BIT_PAT 7 /* on 4KB pages */
#define _PAGE_BIT_GLOBAL 8 /* Global TLB entry PPro+ */
#define _PAGE_BIT_UNUSED1 9 /* available for programmer */
-#define _PAGE_BIT_IOMAP 10 /* flag used to indicate IO
mapping */
+#define _PAGE_BIT_UNUSED2 10 /* available for programmer */
#define _PAGE_BIT_HIDDEN 11 /* hidden by kmemcheck */
#define _PAGE_BIT_PAT_LARGE 12 /* On 2MB or 1GB pages */
#define _PAGE_BIT_SPECIAL _PAGE_BIT_UNUSED1
@@ -41,7 +41,7 @@
#define _PAGE_PSE (_AT(pteval_t, 1) << _PAGE_BIT_PSE)
#define _PAGE_GLOBAL (_AT(pteval_t, 1) << _PAGE_BIT_GLOBAL)
#define _PAGE_UNUSED1 (_AT(pteval_t, 1) << _PAGE_BIT_UNUSED1)
-#define _PAGE_IOMAP (_AT(pteval_t, 1) << _PAGE_BIT_IOMAP)
+#define _PAGE_UNUSED2 (_AT(pteval_t, 1) << _PAGE_BIT_UNUSED2)
#define _PAGE_PAT (_AT(pteval_t, 1) << _PAGE_BIT_PAT)
#define _PAGE_PAT_LARGE (_AT(pteval_t, 1) << _PAGE_BIT_PAT_LARGE)
#define _PAGE_SPECIAL (_AT(pteval_t, 1) << _PAGE_BIT_SPECIAL)
@@ -163,10 +163,10 @@
#define __PAGE_KERNEL_LARGE_NOCACHE (__PAGE_KERNEL | _PAGE_CACHE_UC |
_PAGE_PSE)
#define __PAGE_KERNEL_LARGE_EXEC (__PAGE_KERNEL_EXEC | _PAGE_PSE)
-#define __PAGE_KERNEL_IO (__PAGE_KERNEL | _PAGE_IOMAP)
-#define __PAGE_KERNEL_IO_NOCACHE (__PAGE_KERNEL_NOCACHE | _PAGE_IOMAP)
-#define __PAGE_KERNEL_IO_UC_MINUS (__PAGE_KERNEL_UC_MINUS | _PAGE_IOMAP)
-#define __PAGE_KERNEL_IO_WC (__PAGE_KERNEL_WC | _PAGE_IOMAP)
+#define __PAGE_KERNEL_IO (__PAGE_KERNEL)
+#define __PAGE_KERNEL_IO_NOCACHE (__PAGE_KERNEL_NOCACHE)
+#define __PAGE_KERNEL_IO_UC_MINUS (__PAGE_KERNEL_UC_MINUS)
+#define __PAGE_KERNEL_IO_WC (__PAGE_KERNEL_WC)
#define PAGE_KERNEL __pgprot(__PAGE_KERNEL)
#define PAGE_KERNEL_RO __pgprot(__PAGE_KERNEL_RO)
diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h
index b913915..eb11963 100644
--- a/arch/x86/include/asm/xen/page.h
+++ b/arch/x86/include/asm/xen/page.h
@@ -112,11 +112,18 @@ static inline unsigned long mfn_to_pfn(unsigned long mfn)
pfn = mfn_to_pfn_no_overrides(mfn);
if (get_phys_to_machine(pfn) != mfn) {
/*
- * If this appears to be a foreign mfn (because the pfn
- * doesn't map back to the mfn), then check the local override
- * table to see if there's a better pfn to use.
+ * This is either:
*
- * m2p_find_override_pfn returns ~0 if it doesn't find anything.
+ * a) a foreign MFN with an override.
+ *
+ * b) a foreign MFN without an override.
+ *
+ * c) an identity MFN that is not in the the p2m.
+ *
+ * For (a), look in the m2p overrides. For (b) and
+ * (c) assume identify MFN since mfn_to_pfn() will
+ * only be called on foreign MFNs iff they have
+ * overrides.
*/
pfn = m2p_find_override_pfn(mfn, ~0);
}
@@ -126,8 +133,7 @@ static inline unsigned long mfn_to_pfn(unsigned long mfn)
* entry doesn't map back to the mfn and m2p_override doesn't have a
* valid entry for it.
*/
- if (pfn == ~0 &&
- get_phys_to_machine(mfn) == IDENTITY_FRAME(mfn))
+ if (pfn == ~0)
pfn = mfn;
return pfn;
diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index 4287f1f..9031593 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -537,7 +537,7 @@ static void __init pagetable_init(void)
permanent_kmaps_init(pgd_base);
}
-pteval_t __supported_pte_mask __read_mostly = ~(_PAGE_NX | _PAGE_GLOBAL |
_PAGE_IOMAP);
+pteval_t __supported_pte_mask __read_mostly = ~(_PAGE_NX | _PAGE_GLOBAL);
EXPORT_SYMBOL_GPL(__supported_pte_mask);
/* user-defined highmem size */
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 104d56a..68bf948 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -151,7 +151,7 @@ early_param("gbpages", parse_direct_gbpages_on);
* around without checking the pgd every time.
*/
-pteval_t __supported_pte_mask __read_mostly = ~_PAGE_IOMAP;
+pteval_t __supported_pte_mask __read_mostly = ~0;
EXPORT_SYMBOL_GPL(__supported_pte_mask);
int force_personality32;
diff --git a/arch/x86/pci/i386.c b/arch/x86/pci/i386.c
index db6b1ab..1f642d6 100644
--- a/arch/x86/pci/i386.c
+++ b/arch/x86/pci/i386.c
@@ -433,8 +433,6 @@ int pci_mmap_page_range(struct pci_dev *dev, struct
vm_area_struct *vma,
*/
prot |= _PAGE_CACHE_UC_MINUS;
- prot |= _PAGE_IOMAP; /* creating a mapping for IO */
-
vma->vm_page_prot = __pgprot(prot);
if (io_remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index fa6ade7..f9c2d71 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1458,8 +1458,6 @@ asmlinkage void __init xen_start_kernel(void)
#endif
__supported_pte_mask &= ~(_PAGE_PWT | _PAGE_PCD);
- __supported_pte_mask |= _PAGE_IOMAP;
-
/*
* Prevent page tables from being allocated in highmem, even
* if CONFIG_HIGHPTE is enabled.
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index ce563be..5fa77a1 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -368,11 +368,9 @@ static pteval_t pte_mfn_to_pfn(pteval_t val)
if (val & _PAGE_PRESENT) {
unsigned long mfn = (val & PTE_PFN_MASK) >> PAGE_SHIFT;
unsigned long pfn = mfn_to_pfn(mfn);
-
pteval_t flags = val & PTE_FLAGS_MASK;
- if (unlikely(pfn == ~0))
- val = flags & ~_PAGE_PRESENT;
- else
+
+ if (likely(pfn != ~0))
val = ((pteval_t)pfn << PAGE_SHIFT) | flags;
}
@@ -390,6 +388,7 @@ static pteval_t pte_pfn_to_mfn(pteval_t val)
mfn = get_phys_to_machine(pfn);
else
mfn = pfn;
+
/*
* If there's no mfn for the pfn, then just create an
* empty non-present pte. Unfortunately this loses
@@ -399,38 +398,15 @@ static pteval_t pte_pfn_to_mfn(pteval_t val)
if (unlikely(mfn == INVALID_P2M_ENTRY)) {
mfn = 0;
flags = 0;
- } else {
- /*
- * Paramount to do this test _after_ the
- * INVALID_P2M_ENTRY as INVALID_P2M_ENTRY &
- * IDENTITY_FRAME_BIT resolves to true.
- */
- mfn &= ~FOREIGN_FRAME_BIT;
- if (mfn & IDENTITY_FRAME_BIT) {
- mfn &= ~IDENTITY_FRAME_BIT;
- flags |= _PAGE_IOMAP;
- }
- }
+ mfn = pfn;
+ } else
+ mfn &= ~(FOREIGN_FRAME_BIT | IDENTITY_FRAME_BIT);
val = ((pteval_t)mfn << PAGE_SHIFT) | flags;
}
return val;
}
-static pteval_t iomap_pte(pteval_t val)
-{
- if (val & _PAGE_PRESENT) {
- unsigned long pfn = (val & PTE_PFN_MASK) >> PAGE_SHIFT;
- pteval_t flags = val & PTE_FLAGS_MASK;
-
- /* We assume the pte frame number is a MFN, so
- just use it as-is. */
- val = ((pteval_t)pfn << PAGE_SHIFT) | flags;
- }
-
- return val;
-}
-
static pteval_t xen_pte_val(pte_t pte)
{
pteval_t pteval = pte.pte;
@@ -441,9 +417,6 @@ static pteval_t xen_pte_val(pte_t pte)
pteval = (pteval & ~_PAGE_PAT) | _PAGE_PWT;
}
#endif
- if (xen_initial_domain() && (pteval & _PAGE_IOMAP))
- return pteval;
-
return pte_mfn_to_pfn(pteval);
}
PV_CALLEE_SAVE_REGS_THUNK(xen_pte_val);
@@ -481,7 +454,6 @@ void xen_set_pat(u64 pat)
static pte_t xen_make_pte(pteval_t pte)
{
- phys_addr_t addr = (pte & PTE_PFN_MASK);
#if 0
/* If Linux is trying to set a WC pte, then map to the Xen WC.
* If _PAGE_PAT is set, then it probably means it is really
@@ -496,19 +468,7 @@ static pte_t xen_make_pte(pteval_t pte)
pte = (pte & ~(_PAGE_PCD | _PAGE_PWT)) | _PAGE_PAT;
}
#endif
- /*
- * Unprivileged domains are allowed to do IOMAPpings for
- * PCI passthrough, but not map ISA space. The ISA
- * mappings are just dummy local mappings to keep other
- * parts of the kernel happy.
- */
- if (unlikely(pte & _PAGE_IOMAP) &&
- (xen_initial_domain() || addr >= ISA_END_ADDRESS)) {
- pte = iomap_pte(pte);
- } else {
- pte &= ~_PAGE_IOMAP;
- pte = pte_pfn_to_mfn(pte);
- }
+ pte = pte_pfn_to_mfn(pte);
return native_make_pte(pte);
}
@@ -2084,7 +2044,7 @@ static void xen_set_fixmap(unsigned idx, phys_addr_t
phys, pgprot_t prot)
default:
/* By default, set_fixmap is used for hardware mappings */
- pte = mfn_pte(phys, __pgprot(pgprot_val(prot) | _PAGE_IOMAP));
+ pte = mfn_pte(phys, prot);
break;
}
@@ -2524,8 +2484,6 @@ int xen_remap_domain_mfn_range(struct vm_area_struct *vma,
if (xen_feature(XENFEAT_auto_translated_physmap))
return -EINVAL;
- prot = __pgprot(pgprot_val(prot) | _PAGE_IOMAP);
-
BUG_ON(!((vma->vm_flags & (VM_PFNMAP | VM_IO)) == (VM_PFNMAP | VM_IO)));
rmd.mfn = mfn;
--
1.7.2.5
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