[PATCH 1/1] powerpc: kvm: Reduce calls to get current->mm by storing the value locally

[Leonardo Bras]

Reduces the number of calls to get_current() in order to get the value of
current->mm by doing it once and storing the value, since it is not
supposed to change inside the same process).

Signed-off-by: Leonardo Bras <leona...@linux.ibm.com>
---
 arch/powerpc/kvm/book3s_64_mmu_hv.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c 
b/arch/powerpc/kvm/book3s_64_mmu_hv.c
index 9a75f0e1933b..f2b9aea43216 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
@@ -508,6 +508,7 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct 
kvm_vcpu *vcpu,
        struct vm_area_struct *vma;
        unsigned long rcbits;
        long mmio_update;
+       struct mm_struct *mm;
 
        if (kvm_is_radix(kvm))
                return kvmppc_book3s_radix_page_fault(run, vcpu, ea, dsisr);
@@ -584,6 +585,7 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct 
kvm_vcpu *vcpu,
        is_ci = false;
        pfn = 0;
        page = NULL;
+       mm = current->mm;
        pte_size = PAGE_SIZE;
        writing = (dsisr & DSISR_ISSTORE) != 0;
        /* If writing != 0, then the HPTE must allow writing, if we get here */
@@ -592,8 +594,8 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct 
kvm_vcpu *vcpu,
        npages = get_user_pages_fast(hva, 1, writing ? FOLL_WRITE : 0, pages);
        if (npages < 1) {
                /* Check if it's an I/O mapping */
-               down_read(&current->mm->mmap_sem);
-               vma = find_vma(current->mm, hva);
+               down_read(&mm->mmap_sem);
+               vma = find_vma(mm, hva);
                if (vma && vma->vm_start <= hva && hva + psize <= vma->vm_end &&
                    (vma->vm_flags & VM_PFNMAP)) {
                        pfn = vma->vm_pgoff +
@@ -602,7 +604,7 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct 
kvm_vcpu *vcpu,
                        is_ci = pte_ci(__pte((pgprot_val(vma->vm_page_prot))));
                        write_ok = vma->vm_flags & VM_WRITE;
                }
-               up_read(&current->mm->mmap_sem);
+               up_read(&mm->mmap_sem);
                if (!pfn)
                        goto out_put;
        } else {
@@ -621,8 +623,7 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct 
kvm_vcpu *vcpu,
                         * hugepage split and collapse.
                         */
                        local_irq_save(flags);
-                       ptep = find_current_mm_pte(current->mm->pgd,
-                                                  hva, NULL, NULL);
+                       ptep = find_current_mm_pte(mm->pgd, hva, NULL, NULL);
                        if (ptep) {
                                pte = kvmppc_read_update_linux_pte(ptep, 1);
                                if (__pte_write(pte))
-- 
2.20.1