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Subject[PATCH 08/19] xen/dom0: use _PAGE_IOMAP in ioremap to do machine mappings
Date
In a Xen domain, ioremap operates on machine addresses, not
pseudo-physical addresses. We use _PAGE_IOMAP to determine whether a
mapping is intended for machine addresses.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
---
arch/x86/include/asm/xen/page.h | 8 +---
arch/x86/xen/enlighten.c | 4 ++-
arch/x86/xen/mmu.c | 70 +++++++++++++++++++++++++++++++++++++-
3 files changed, 73 insertions(+), 9 deletions(-)
diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h
index 4bd990e..20c3872 100644
--- a/arch/x86/include/asm/xen/page.h
+++ b/arch/x86/include/asm/xen/page.h
@@ -112,13 +112,9 @@ static inline xpaddr_t machine_to_phys(xmaddr_t machine)
*/
static inline unsigned long mfn_to_local_pfn(unsigned long mfn)
{
- extern unsigned long max_mapnr;
unsigned long pfn = mfn_to_pfn(mfn);
- if ((pfn < max_mapnr)
- && !xen_feature(XENFEAT_auto_translated_physmap)
- && (get_phys_to_machine(pfn) != mfn))
- return max_mapnr; /* force !pfn_valid() */
- /* XXX fixme; not true with sparsemem */
+ if (get_phys_to_machine(pfn) != mfn)
+ return -1; /* force !pfn_valid() */
return pfn;
}

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 1b89d1c..c12a3c8 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -938,7 +938,9 @@ asmlinkage void __init xen_start_kernel(void)

/* Prevent unwanted bits from being set in PTEs. */
__supported_pte_mask &= ~_PAGE_GLOBAL;
- if (!xen_initial_domain())
+ if (xen_initial_domain())
+ __supported_pte_mask |= _PAGE_IOMAP;
+ else
__supported_pte_mask &= ~(_PAGE_PWT | _PAGE_PCD);

/* Don't do the full vcpu_info placement stuff until we have a
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 36125ea..6aa6d55 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -336,6 +336,28 @@ static bool xen_page_pinned(void *ptr)
return PagePinned(page);
}

+static bool xen_iomap_pte(pte_t pte)
+{
+ return xen_initial_domain() && (pte_flags(pte) & _PAGE_IOMAP);
+}
+
+static void xen_set_iomap_pte(pte_t *ptep, pte_t pteval)
+{
+ struct multicall_space mcs;
+ struct mmu_update *u;
+
+ mcs = xen_mc_entry(sizeof(*u));
+ u = mcs.args;
+
+ /* ptep might be kmapped when using 32-bit HIGHPTE */
+ u->ptr = arbitrary_virt_to_machine(ptep).maddr;
+ u->val = pte_val_ma(pteval);
+
+ MULTI_mmu_update(mcs.mc, mcs.args, 1, NULL, DOMID_IO);
+
+ xen_mc_issue(PARAVIRT_LAZY_MMU);
+}
+
static void xen_extend_mmu_update(const struct mmu_update *update)
{
struct multicall_space mcs;
@@ -416,6 +438,11 @@ void xen_set_pte_at(struct mm_struct *mm, unsigned long addr,
if (mm == &init_mm)
preempt_disable();

+ if (xen_iomap_pte(pteval)) {
+ xen_set_iomap_pte(ptep, pteval);
+ goto out;
+ }
+
ADD_STATS(set_pte_at, 1);
// ADD_STATS(set_pte_at_pinned, xen_page_pinned(ptep));
ADD_STATS(set_pte_at_current, mm == current->mm);
@@ -488,8 +515,25 @@ static pteval_t pte_pfn_to_mfn(pteval_t val)
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;
+}
+
pteval_t xen_pte_val(pte_t pte)
{
+ if (xen_initial_domain() && (pte.pte & _PAGE_IOMAP))
+ return pte.pte;
+
return pte_mfn_to_pfn(pte.pte);
}
PV_CALLEE_SAVE_REGS_THUNK(xen_pte_val);
@@ -502,7 +546,11 @@ PV_CALLEE_SAVE_REGS_THUNK(xen_pgd_val);

pte_t xen_make_pte(pteval_t pte)
{
- pte = pte_pfn_to_mfn(pte);
+ if (unlikely(xen_initial_domain() && (pte & _PAGE_IOMAP)))
+ pte = iomap_pte(pte);
+ else
+ pte = pte_pfn_to_mfn(pte);
+
return native_make_pte(pte);
}
PV_CALLEE_SAVE_REGS_THUNK(xen_make_pte);
@@ -558,6 +606,11 @@ void xen_set_pud(pud_t *ptr, pud_t val)

void xen_set_pte(pte_t *ptep, pte_t pte)
{
+ if (xen_iomap_pte(pte)) {
+ xen_set_iomap_pte(ptep, pte);
+ return;
+ }
+
ADD_STATS(pte_update, 1);
// ADD_STATS(pte_update_pinned, xen_page_pinned(ptep));
ADD_STATS(pte_update_batched, paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU);
@@ -574,6 +627,11 @@ void xen_set_pte(pte_t *ptep, pte_t pte)
#ifdef CONFIG_X86_PAE
void xen_set_pte_atomic(pte_t *ptep, pte_t pte)
{
+ if (xen_iomap_pte(pte)) {
+ xen_set_iomap_pte(ptep, pte);
+ return;
+ }
+
set_64bit((u64 *)ptep, native_pte_val(pte));
}

@@ -1770,12 +1828,20 @@ static void xen_set_fixmap(unsigned idx, unsigned long phys, pgprot_t prot)
#ifdef CONFIG_X86_LOCAL_APIC
case FIX_APIC_BASE: /* maps dummy local APIC */
#endif
+ /* All local page mappings */
pte = pfn_pte(phys, prot);
break;

- default:
+ case FIX_PARAVIRT_BOOTMAP:
+ /* This is an MFN, but it isn't an IO mapping from the
+ IO domain */
pte = mfn_pte(phys, prot);
break;
+
+ default:
+ /* By default, set_fixmap is used for hardware mappings */
+ pte = mfn_pte(phys, __pgprot(pgprot_val(prot) | _PAGE_IOMAP));
+ break;
}

__native_set_fixmap(idx, pte);
--
1.6.0.6


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