From a99ac5e8619c27dbb8e7fb5a4e0ca8c8aa214909 Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Wed, 1 Dec 2010 15:13:34 -0800 Subject: xen: use mmu_update for xen_set_pte_at() In principle update_va_mapping is a good match for set_pte_at, since it gets the address being mapped, which allows Xen to use its linear pagetable mapping. However that assumes that the pmd for the address is attached to the current pagetable, which may not be true for a given user address space because the kernel pmd is not shared (at least on 32-bit guests). Normally the kernel will automatically sync a missing part of the pagetable with the init_mm pagetable transparently via faults, but that fails when a missing address is passed to Xen. And while the linear pagetable mapping is very useful for 32-bit Xen (as it avoids an explicit domain mapping), 32-bit Xen is deprecated. 64-bit Xen has all memory mapped all the time, so it makes no real difference. The upshot is that we should use mmu_update, since it can operate on non-current pagetables or detached pagetables. Signed-off-by: Jeremy Fitzhardinge --- arch/x86/xen/mmu.c | 26 +++++++++++--------------- 1 file changed, 11 insertions(+), 15 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c index 4f5e0dc..fb3e92e 100644 --- a/arch/x86/xen/mmu.c +++ b/arch/x86/xen/mmu.c @@ -342,22 +342,18 @@ void xen_set_pte_at(struct mm_struct *mm, unsigned long addr, ADD_STATS(set_pte_at_current, mm == current->mm); ADD_STATS(set_pte_at_kernel, mm == &init_mm); - if (mm == current->mm || mm == &init_mm) { - if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) { - struct multicall_space mcs; - mcs = xen_mc_entry(0); - - MULTI_update_va_mapping(mcs.mc, addr, pteval, 0); - ADD_STATS(set_pte_at_batched, 1); - xen_mc_issue(PARAVIRT_LAZY_MMU); - goto out; - } else - if (HYPERVISOR_update_va_mapping(addr, pteval, 0) == 0) - goto out; - } - xen_set_pte(ptep, pteval); + if(paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) { + struct mmu_update u; + + xen_mc_batch(); + + u.ptr = virt_to_machine(ptep).maddr | MMU_NORMAL_PT_UPDATE; + u.val = pte_val_ma(pteval); + xen_extend_mmu_update(&u); -out: return; + xen_mc_issue(PARAVIRT_LAZY_MMU); + } else + native_set_pte(ptep, pteval); } pte_t xen_ptep_modify_prot_start(struct mm_struct *mm, -- cgit v1.1