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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 <ian.campbell@citrix.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
This commit is contained in:
Ian Campbell 2009-05-20 15:42:14 +01:00 committed by Jeremy Fitzhardinge
parent 8e3e99918b
commit f020e29051
1 changed files with 41 additions and 15 deletions
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52
drivers/xen/xenfs/privcmd.c
View File

@ -32,14 +32,16 @@
#include <xen/features.h>
#include <xen/page.h>
#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,
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,
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);