From f020e2905166e12f9a8f109fe968cb5a9db887e9 Mon Sep 17 00:00:00 2001 From: Ian Campbell Date: Wed, 20 May 2009 15:42:14 +0100 Subject: [PATCH] privcmd: MMAPBATCH: Fix error handling/reporting On error IOCTL_PRIVCMD_MMAPBATCH is expected to set the top nibble of the effected MFN and return 0. Currently it leaves the MFN unmodified and returns the number of failures. Therefore: - reimplement remap_domain_mfn_range() using direct HYPERVISOR_mmu_update() calls and small batches. The xen_set_domain_pte() interface does not report errors and since some failures are expected/normal using the multicall infrastructure is too noisy. - return 0 as expected - writeback the updated MFN list to mmapbatch->arr not over mmapbatch, smashing the caller's stack. - remap_domain_mfn_range can be static. With this change I am able to start an HVM domain. Signed-off-by: Ian Campbell Cc: Jeremy Fitzhardinge Signed-off-by: Jeremy Fitzhardinge --- drivers/xen/xenfs/privcmd.c | 56 +++++++++++++++++++++++++++---------- 1 file changed, 41 insertions(+), 15 deletions(-) diff --git a/drivers/xen/xenfs/privcmd.c b/drivers/xen/xenfs/privcmd.c index 80526afd3063..438223ae0fc3 100644 --- a/drivers/xen/xenfs/privcmd.c +++ b/drivers/xen/xenfs/privcmd.c @@ -32,14 +32,16 @@ #include #include +#define REMAP_BATCH_SIZE 16 + #ifndef HAVE_ARCH_PRIVCMD_MMAP static int privcmd_enforce_singleshot_mapping(struct vm_area_struct *vma); #endif struct remap_data { unsigned long mfn; - unsigned domid; pgprot_t prot; + struct mmu_update *mmu_update; }; static int remap_area_mfn_pte_fn(pte_t *ptep, pgtable_t token, @@ -48,17 +50,23 @@ static int remap_area_mfn_pte_fn(pte_t *ptep, pgtable_t token, struct remap_data *rmd = data; pte_t pte = pte_mkspecial(pfn_pte(rmd->mfn++, rmd->prot)); - xen_set_domain_pte(ptep, pte, rmd->domid); + rmd->mmu_update->ptr = arbitrary_virt_to_machine(ptep).maddr; + rmd->mmu_update->val = pte_val_ma(pte); + rmd->mmu_update++; return 0; } -int remap_domain_mfn_range(struct vm_area_struct *vma, unsigned long addr, - unsigned long mfn, unsigned long size, - pgprot_t prot, unsigned domid) +static int remap_domain_mfn_range(struct vm_area_struct *vma, + unsigned long addr, + unsigned long mfn, int nr, + pgprot_t prot, unsigned domid) { struct remap_data rmd; - int err; + struct mmu_update mmu_update[REMAP_BATCH_SIZE]; + int batch; + unsigned long range; + int err = 0; prot = __pgprot(pgprot_val(prot) | _PAGE_IOMAP); @@ -66,10 +74,29 @@ int remap_domain_mfn_range(struct vm_area_struct *vma, unsigned long addr, rmd.mfn = mfn; rmd.prot = prot; - rmd.domid = domid; - err = apply_to_page_range(vma->vm_mm, addr, size, - remap_area_mfn_pte_fn, &rmd); + while (nr) { + batch = min(REMAP_BATCH_SIZE, nr); + range = (unsigned long)batch << PAGE_SHIFT; + + rmd.mmu_update = mmu_update; + err = apply_to_page_range(vma->vm_mm, addr, range, + remap_area_mfn_pte_fn, &rmd); + if (err) + goto out; + + err = -EFAULT; + if (HYPERVISOR_mmu_update(mmu_update, batch, NULL, domid) < 0) + goto out; + + nr -= batch; + addr += range; + } + + err = 0; +out: + + flush_tlb_all(); return err; } @@ -158,7 +185,7 @@ static int traverse_pages(unsigned nelem, size_t size, { void *pagedata; unsigned pageidx; - int ret; + int ret = 0; BUG_ON(size > PAGE_SIZE); @@ -208,8 +235,7 @@ static int mmap_mfn_range(void *data, void *state) rc = remap_domain_mfn_range(vma, msg->va & PAGE_MASK, - msg->mfn, - msg->npages << PAGE_SHIFT, + msg->mfn, msg->npages, vma->vm_page_prot, st->domain); if (rc < 0) @@ -290,7 +316,7 @@ static int mmap_batch_fn(void *data, void *state) struct mmap_batch_state *st = state; if (remap_domain_mfn_range(st->vma, st->va & PAGE_MASK, - *mfnp, PAGE_SIZE, + *mfnp, 1, st->vma->vm_page_prot, st->domain) < 0) { *mfnp |= 0xf0000000U; st->err++; @@ -362,9 +388,9 @@ static long privcmd_ioctl_mmap_batch(void __user *udata) up_write(&mm->mmap_sem); if (state.err > 0) { - ret = state.err; + ret = 0; - state.user = udata; + state.user = m.arr; traverse_pages(m.num, sizeof(xen_pfn_t), &pagelist, mmap_return_errors, &state);