Boris Derzhavets
2009-May-20 19:22 UTC
Re: [Xen-devel] [PATCH] privcmd: MMAPBATCH: Fix error handling/reporting
How long it takes for your patches to get in
git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen.git ?
Boris.
--- On Wed, 5/20/09, Ian Campbell <ian.campbell@citrix.com> wrote:
From: Ian Campbell <ian.campbell@citrix.com>
Subject: [Xen-devel] [PATCH] privcmd: MMAPBATCH: Fix error handling/reporting
To: xen-devel@lists.xensource.com
Cc: "Jeremy Fitzhardinge" <jeremy@goop.org>, "Ian
Campbell" <ian.campbell@citrix.com>
Date: Wednesday, May 20, 2009, 10:45 AM
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>
---
drivers/xen/xenfs/privcmd.c | 56 +++++++++++++++++++++++++++++++-----------
1 files changed, 41 insertions(+), 15 deletions(-)
diff --git a/drivers/xen/xenfs/privcmd.c b/drivers/xen/xenfs/privcmd.c
index 263f622..110b062 100644
--- a/drivers/xen/xenfs/privcmd.c
+++ b/drivers/xen/xenfs/privcmd.c
@@ -31,14 +31,16 @@
#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,
@@ -47,17 +49,23 @@ 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);
@@ -65,10 +73,29 @@ 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;
}
@@ -157,7 +184,7 @@ static int traverse_pages(unsigned nelem, size_t size,
{
void *pagedata;
unsigned pageidx;
- int ret;
+ int ret = 0;
BUG_ON(size > PAGE_SIZE);
@@ -207,8 +234,7 @@ 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)
@@ -289,7 +315,7 @@ 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++;
@@ -361,9 +387,9 @@ 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);
--
1.5.6.5
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