From 4e8c0c8c4bf3a5b5c98046e146ab3884bf7a7d0e Mon Sep 17 00:00:00 2001 From: David Vrabel Date: Wed, 11 Mar 2015 14:49:57 +0000 Subject: xen/privcmd: improve performance of MMAPBATCH_V2 Make the IOCTL_PRIVCMD_MMAPBATCH_V2 (and older V1 version) map multiple frames at a time rather than one at a time, despite the pages being non-consecutive GFNs. xen_remap_foreign_mfn_array() is added which maps an array of GFNs (instead of a consecutive range of GFNs). Since per-frame errors are returned in an array, privcmd must set the MMAPBATCH_V1 error bits as part of the "report errors" phase, after all the frames are mapped. Migrate times are significantly improved (when using a PV toolstack domain). For example, for an idle 12 GiB PV guest: Before After real 0m38.179s 0m26.868s user 0m15.096s 0m13.652s sys 0m28.988s 0m18.732s Signed-off-by: David Vrabel Reviewed-by: Stefano Stabellini --- arch/x86/xen/mmu.c | 101 +++++++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 82 insertions(+), 19 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c index 3d536a56ddf1..29b3be230ede 100644 --- a/arch/x86/xen/mmu.c +++ b/arch/x86/xen/mmu.c @@ -2439,7 +2439,8 @@ void __init xen_hvm_init_mmu_ops(void) #define REMAP_BATCH_SIZE 16 struct remap_data { - unsigned long mfn; + xen_pfn_t *mfn; + bool contiguous; pgprot_t prot; struct mmu_update *mmu_update; }; @@ -2448,7 +2449,14 @@ static int remap_area_mfn_pte_fn(pte_t *ptep, pgtable_t token, unsigned long addr, void *data) { struct remap_data *rmd = data; - pte_t pte = pte_mkspecial(mfn_pte(rmd->mfn++, rmd->prot)); + pte_t pte = pte_mkspecial(mfn_pte(*rmd->mfn, rmd->prot)); + + /* If we have a contigious range, just update the mfn itself, + else update pointer to be "next mfn". */ + if (rmd->contiguous) + (*rmd->mfn)++; + else + rmd->mfn++; rmd->mmu_update->ptr = virt_to_machine(ptep).maddr; rmd->mmu_update->val = pte_val_ma(pte); @@ -2457,26 +2465,26 @@ static int remap_area_mfn_pte_fn(pte_t *ptep, pgtable_t token, return 0; } -int xen_remap_domain_mfn_range(struct vm_area_struct *vma, - unsigned long addr, - xen_pfn_t mfn, int nr, - pgprot_t prot, unsigned domid, - struct page **pages) - +static int do_remap_mfn(struct vm_area_struct *vma, + unsigned long addr, + xen_pfn_t *mfn, int nr, + int *err_ptr, pgprot_t prot, + unsigned domid, + struct page **pages) { + int err = 0; struct remap_data rmd; struct mmu_update mmu_update[REMAP_BATCH_SIZE]; - int batch; unsigned long range; - int err = 0; + int mapped = 0; BUG_ON(!((vma->vm_flags & (VM_PFNMAP | VM_IO)) == (VM_PFNMAP | VM_IO))); if (xen_feature(XENFEAT_auto_translated_physmap)) { #ifdef CONFIG_XEN_PVH /* We need to update the local page tables and the xen HAP */ - return xen_xlate_remap_gfn_range(vma, addr, mfn, nr, prot, - domid, pages); + return xen_xlate_remap_gfn_array(vma, addr, mfn, nr, err_ptr, + prot, domid, pages); #else return -EINVAL; #endif @@ -2484,9 +2492,15 @@ int xen_remap_domain_mfn_range(struct vm_area_struct *vma, rmd.mfn = mfn; rmd.prot = prot; + /* We use the err_ptr to indicate if there we are doing a contigious + * mapping or a discontigious mapping. */ + rmd.contiguous = !err_ptr; while (nr) { - batch = min(REMAP_BATCH_SIZE, nr); + int index = 0; + int done = 0; + int batch = min(REMAP_BATCH_SIZE, nr); + int batch_left = batch; range = (unsigned long)batch << PAGE_SHIFT; rmd.mmu_update = mmu_update; @@ -2495,23 +2509,72 @@ int xen_remap_domain_mfn_range(struct vm_area_struct *vma, if (err) goto out; - err = HYPERVISOR_mmu_update(mmu_update, batch, NULL, domid); - if (err < 0) - goto out; + /* We record the error for each page that gives an error, but + * continue mapping until the whole set is done */ + do { + int i; + + err = HYPERVISOR_mmu_update(&mmu_update[index], + batch_left, &done, domid); + + /* + * @err_ptr may be the same buffer as @mfn, so + * only clear it after each chunk of @mfn is + * used. + */ + if (err_ptr) { + for (i = index; i < index + done; i++) + err_ptr[i] = 0; + } + if (err < 0) { + if (!err_ptr) + goto out; + err_ptr[i] = err; + done++; /* Skip failed frame. */ + } else + mapped += done; + batch_left -= done; + index += done; + } while (batch_left); nr -= batch; addr += range; + if (err_ptr) + err_ptr += batch; } - - err = 0; out: xen_flush_tlb_all(); - return err; + return err < 0 ? err : mapped; +} + +int xen_remap_domain_mfn_range(struct vm_area_struct *vma, + unsigned long addr, + xen_pfn_t mfn, int nr, + pgprot_t prot, unsigned domid, + struct page **pages) +{ + return do_remap_mfn(vma, addr, &mfn, nr, NULL, prot, domid, pages); } EXPORT_SYMBOL_GPL(xen_remap_domain_mfn_range); +int xen_remap_domain_mfn_array(struct vm_area_struct *vma, + unsigned long addr, + xen_pfn_t *mfn, int nr, + int *err_ptr, pgprot_t prot, + unsigned domid, struct page **pages) +{ + /* We BUG_ON because it's a programmer error to pass a NULL err_ptr, + * and the consequences later is quite hard to detect what the actual + * cause of "wrong memory was mapped in". + */ + BUG_ON(err_ptr == NULL); + return do_remap_mfn(vma, addr, mfn, nr, err_ptr, prot, domid, pages); +} +EXPORT_SYMBOL_GPL(xen_remap_domain_mfn_array); + + /* Returns: 0 success */ int xen_unmap_domain_mfn_range(struct vm_area_struct *vma, int numpgs, struct page **pages) -- cgit v1.2.3