[Xen-devel] [PATCH 3/9] x86/paravirt: remove lazy mode in interrupts

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

From: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>

Make paravirt_lazy_mode() always return PARAVIRT_LAZY_NONE
when in an interrupt.  This prevents interrupt code from
accidentally inheriting an outer lazy state, and instead
does everything synchronously.  Outer batched operations
are left deferred.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
---
 arch/x86/kernel/paravirt.c |    3 +++
 arch/x86/mm/fault.c        |    5 ++---
 arch/x86/mm/highmem_32.c   |    3 ---
 arch/x86/mm/iomap_32.c     |    2 --
 arch/x86/mm/pageattr.c     |   14 --------------
 5 files changed, 5 insertions(+), 22 deletions(-)

diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index 6dc4dca..83dadf9 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -283,6 +283,9 @@ void paravirt_leave_lazy_cpu(void)
 
 enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
 {
+       if (in_interrupt())
+               return PARAVIRT_LAZY_NONE;
+
        return __get_cpu_var(paravirt_lazy_mode);
 }
 
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 6b9239d..51b352a 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -296,10 +296,9 @@ static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned 
long address)
        pmd_k = pmd_offset(pud_k, address);
        if (!pmd_present(*pmd_k))
                return NULL;
-       if (!pmd_present(*pmd)) {
+       if (!pmd_present(*pmd))
                set_pmd(pmd, *pmd_k);
-               arch_flush_lazy_mmu_mode();
-       } else
+       else
                BUG_ON(pmd_page(*pmd) != pmd_page(*pmd_k));
        return pmd_k;
 }
diff --git a/arch/x86/mm/highmem_32.c b/arch/x86/mm/highmem_32.c
index bcc079c..98c9ac7 100644
--- a/arch/x86/mm/highmem_32.c
+++ b/arch/x86/mm/highmem_32.c
@@ -86,7 +86,6 @@ void *kmap_atomic_prot(struct page *page, enum km_type type, 
pgprot_t prot)
        vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
        BUG_ON(!pte_none(*(kmap_pte-idx)));
        set_pte(kmap_pte-idx, mk_pte(page, prot));
-       arch_flush_lazy_mmu_mode();
 
        return (void *)vaddr;
 }
@@ -116,7 +115,6 @@ void kunmap_atomic(void *kvaddr, enum km_type type)
 #endif
        }
 
-       arch_flush_lazy_mmu_mode();
        pagefault_enable();
 }
 
@@ -133,7 +131,6 @@ void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
        idx = type + KM_TYPE_NR*smp_processor_id();
        vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
        set_pte(kmap_pte-idx, pfn_pte(pfn, kmap_prot));
-       arch_flush_lazy_mmu_mode();
 
        return (void*) vaddr;
 }
diff --git a/arch/x86/mm/iomap_32.c b/arch/x86/mm/iomap_32.c
index ca53224..a75f8bb 100644
--- a/arch/x86/mm/iomap_32.c
+++ b/arch/x86/mm/iomap_32.c
@@ -42,7 +42,6 @@ iomap_atomic_prot_pfn(unsigned long pfn, enum km_type type, 
pgprot_t prot)
        idx = type + KM_TYPE_NR*smp_processor_id();
        vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
        set_pte(kmap_pte-idx, pfn_pte(pfn, prot));
-       arch_flush_lazy_mmu_mode();
 
        return (void*) vaddr;
 }
@@ -63,7 +62,6 @@ iounmap_atomic(void *kvaddr, enum km_type type)
        if (vaddr == __fix_to_virt(FIX_KMAP_BEGIN+idx))
                kpte_clear_flush(kmap_pte-idx, vaddr);
 
-       arch_flush_lazy_mmu_mode();
        pagefault_enable();
 }
 EXPORT_SYMBOL_GPL(iounmap_atomic);
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 8ca0d85..52460f9 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -811,13 +811,6 @@ static int change_page_attr_set_clr(unsigned long *addr, 
int numpages,
 
        vm_unmap_aliases();
 
-       /*
-        * If we're called with lazy mmu updates enabled, the
-        * in-memory pte state may be stale.  Flush pending updates to
-        * bring them up to date.
-        */
-       arch_flush_lazy_mmu_mode();
-
        cpa.vaddr = addr;
        cpa.numpages = numpages;
        cpa.mask_set = mask_set;
@@ -860,13 +853,6 @@ static int change_page_attr_set_clr(unsigned long *addr, 
int numpages,
        } else
                cpa_flush_all(cache);
 
-       /*
-        * If we've been called with lazy mmu updates enabled, then
-        * make sure that everything gets flushed out before we
-        * return.
-        */
-       arch_flush_lazy_mmu_mode();
-
 out:
        return ret;
 }
-- 
1.6.0.6


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