x86/paravirt: remove lazy mode in interrupts

Impact: simplification, robustness

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@citrix.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>

5 files changed, 5 insertions, 21 deletions

diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index 63dd358d8ee..8ab250ac498 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -282,6 +282,9 @@ 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 a03b7279efa..cfbb4a73801 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -225,12 +225,10 @@ static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long 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 00f127c80b0..e81dfa40815 100644
--- a/arch/x86/mm/highmem_32.c
+++ b/arch/x86/mm/highmem_32.c
@@ -87,7 +87,6 @@ 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;
 }
@@ -117,7 +116,6 @@ void kunmap_atomic(void *kvaddr, enum km_type type)
 #endif
         }
 
-        arch_flush_lazy_mmu_mode();
         pagefault_enable();
 }
 
diff --git a/arch/x86/mm/iomap_32.c b/arch/x86/mm/iomap_32.c
index 04102d42ff4..b6a61f3d7ef 100644
--- a/arch/x86/mm/iomap_32.c
+++ b/arch/x86/mm/iomap_32.c
@@ -74,7 +74,6 @@ 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 9c4294986af..9015e5e412b 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -824,13 +824,6 @@ 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;
@@ -873,13 +866,6 @@ 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;
 }