On 05/25/2010 09:40 PM, Jan Kiszka wrote:
Zachary Amsden wrote:
On 05/25/2010 05:36 PM, Zachary Amsden wrote:
Not for the faint of heart, this patch subverts the code by
reassigning a local variable from a macro.
This time, with patch.
From 97b9230f699aba1c5f47972032b2d4d935a83054 Mon Sep 17 00:00:00 2001
From: Zachary Amsden<zamsden@xxxxxxxxxx>
Date: Tue, 25 May 2010 17:17:32 -1000
Subject: [PATCH 4/5] IOMMU API changed
Ugly, dirty, disease ridden fix for IOMMU changes; the module
is now trying to use larger IOMMU intervals; deny it this, and
stick to page size. This requires forcibly setting page_size
variable through knowledge of the code. Yuck. If you have a
better solution, implement it.
Signed-off-by: Zachary Amsden<zamsden@xxxxxxxxxx>
---
external-module-compat-comm.h | 12 ++++++++++++
1 files changed, 12 insertions(+), 0 deletions(-)
diff --git a/external-module-compat-comm.h b/external-module-compat-comm.h
index c5284e5..708019e 100644
--- a/external-module-compat-comm.h
+++ b/external-module-compat-comm.h
@@ -1128,3 +1128,15 @@ perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
#if LINUX_VERSION_CODE< KERNEL_VERSION(2,6,32)
#define lockdep_is_held(m) (1)
#endif
+
+#if LINUX_VERSION_CODE< KERNEL_VERSION(2,6,34)
+/* This is a dirty, nasty trick */
+#define iommu_map(domain, iova, paddr, gfp_order, prot) \
+({ \
+ int _r = iommu_map_range(domain, iova, paddr, PAGE_SIZE, prot); \
This should be (PAGE_SIZE<< gfp_order) according to my current
understanding.
It should, but can't be.
+ page_size = PAGE_SIZE; \
And what is this for?
iommu_unmap is now passed an unreasonable value for order: PAGE_SIZE.
The way the code work, that ends up becoming zero, then -1, for an
infinite sized unmap (if I'm reading correctly). Then iommu_unmap_range
returns the gfp_order of the unmap which it actually did.
Since we have no way to know the size of the original map, I
deliberately force all mappings to be in units of PAGE_SIZE. This
requires changing the local variable page_size in the following code.
(Note the pin is unchanged, so we are doubling pinning... maybe this is
causing my bug).
/*
* Pin all pages we are about to map in memory. This is
* important because we unmap and unpin in 4kb steps later.
*/
pfn = kvm_pin_pages(kvm, slot, gfn, page_size);
if (is_error_pfn(pfn)) {
gfn += 1;
continue;
}
/* Map into IO address space */
r = iommu_map(domain, gfn_to_gpa(gfn), pfn_to_hpa(pfn),
get_order(page_size), flags);
if (r) {
printk(KERN_ERR "kvm_iommu_map_address:"
"iommu failed to map pfn=%lx\n", pfn);
goto unmap_pages;
}
gfn += page_size >> PAGE_SHIFT;
In any case, fixing the gfn computation is needed so the unmap can work:
while (gfn < end_gfn) {
unsigned long unmap_pages;
int order;
/* Get physical address */
phys = iommu_iova_to_phys(domain, gfn_to_gpa(gfn));
pfn = phys >> PAGE_SHIFT;
/* Unmap address from IO address space */
order = iommu_unmap(domain, gfn_to_gpa(gfn), PAGE_SIZE);
unmap_pages = 1ULL << order;
/* Unpin all pages we just unmapped to not leak any memory */
kvm_unpin_pages(kvm, pfn, unmap_pages);
gfn += unmap_pages;
}
Note iommu_unmap(,,PAGE_SIZE) is a bogus argument.
+ _r; \
+})
+#define iommu_unmap(domain, iova, gfp_order) \
+ (iommu_unmap_range(domain, iova, PAGE_SIZE),1)
+#endif
-- 1.7.0.1
Besides that, putting this under CONFIG_IOMMU_API and making the
functions static inline would be preferred.
Jan
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