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Re: [Xen-devel] [PATCH FOR-4.5] xen: arm64: Handle memory banks which are not 1GB aligned
On 10/10/2014 9:43 AM, Ian Campbell wrote:
The code in the arm64 version of setup_xenheap_mappings was making
some very confused attempts to handle this but was bogus.
As well as adjusting the mapping to start on a 1GB boundary we also
need to account for the offset between the start of the mapping and
the actual start of the heap when converting between page pointers,
virtual addresses and machine addresses.
I preferred to do this by explicitly accounting for the offset rather
than adding an offset to the frametable because that approach could
potentially waste a large amount of frametable (up to just less than
1GB worth) but also because of issues with converting mfns from
outside the regions considered for pdx initialisation (which are not
1GB aligned) back and forth.
We already have an idea of the distinction between the start of the
direct map and the start of the xenheap in the difference between
DIRECTMAP_VIRT_START and XENHEAP_VIRT_START. Until now these were the
same thing, but now we change XENHEAP_VIRT_START to point to the
actual start of heap not the mapping. Surprisingly there was only one
place which was using the conceptually wrong value.
Also change xenheap_virt_end to a vaddr_t for consistency.
We've been lucky so far that most hardware happens to locate memory
on a 1GB boundary (we did have reports of a system with memory at a
half gig boundary which exhibited failures which I didn't manage to
follow up on successfully). The EFI support has exposed this
shortcoming by the way it handles reserved memory, which has a
similar effect to having memory non-1GB aligned.
arm32 does things differently here due to using a small Xen heap and
a demand mapped domain heap, so isn't affected.
Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Cc: Suravee Suthikulanit <suravee.suthikulpanit@xxxxxxx>
Cc: Roy Franz <roy.franz@xxxxxxxxxx>
Cc: Vijay Kilari <vijay.kilari@xxxxxxxxx>
---
FOR-4.5: This is a bug fix.
---
xen/arch/arm/mm.c | 36 +++++++++++++++++++++++++-----------
xen/include/asm-arm/config.h | 2 +-
xen/include/asm-arm/mm.h | 7 +++++--
3 files changed, 31 insertions(+), 14 deletions(-)
diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index c5b48ef..97e5bc39 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -138,7 +138,10 @@ static paddr_t phys_offset;
/* Limits of the Xen heap */
unsigned long xenheap_mfn_start __read_mostly = ~0UL;
unsigned long xenheap_mfn_end __read_mostly;
-unsigned long xenheap_virt_end __read_mostly;
+vaddr_t xenheap_virt_end __read_mostly;
+#ifdef CONFIG_ARM_64
+vaddr_t xenheap_virt_start __read_mostly;
+#endif
unsigned long frametable_base_pdx __read_mostly;
unsigned long frametable_virt_end __read_mostly;
@@ -155,7 +158,11 @@ static inline void
check_memory_layout_alignment_constraints(void) {
BUILD_BUG_ON(FIXMAP_ADDR(0) & ~SECOND_MASK);
BUILD_BUG_ON(BOOT_RELOC_VIRT_START & ~SECOND_MASK);
/* 1GB aligned regions */
+#ifdef CONFIG_ARM_32
BUILD_BUG_ON(XENHEAP_VIRT_START & ~FIRST_MASK);
+#else
+ BUILD_BUG_ON(DIRECTMAP_VIRT_START & ~FIRST_MASK);
+#endif
/* Page table structure constraints */
#ifdef CONFIG_ARM_64
BUILD_BUG_ON(zeroeth_table_offset(XEN_VIRT_START));
@@ -665,12 +672,19 @@ void __init setup_xenheap_mappings(unsigned long base_mfn,
unsigned long nr_mfns)
{
lpae_t *first, pte;
- unsigned long offset, end_mfn;
+ unsigned long mfn, end_mfn;
vaddr_t vaddr;
- /* First call sets the xenheap physical offset. */
+ /* Align to previous 1GB boundary */
+ mfn = base_mfn & ~((FIRST_SIZE>>PAGE_SHIFT)-1);
+
+ /* First call sets the xenheap physical and virtual offset. */
if ( xenheap_mfn_start == ~0UL )
+ {
xenheap_mfn_start = base_mfn;
+ xenheap_virt_start = DIRECTMAP_VIRT_START +
+ (base_mfn - mfn) * PAGE_SIZE;
+ }
if ( base_mfn < xenheap_mfn_start )
panic("cannot add xenheap mapping at %lx below heap start %lx",
@@ -678,13 +692,13 @@ void __init setup_xenheap_mappings(unsigned long base_mfn,
end_mfn = base_mfn + nr_mfns;
- /* Align to previous 1GB boundary */
- base_mfn &= ~((FIRST_SIZE>>PAGE_SHIFT)-1);
-
- offset = pfn_to_pdx(base_mfn - xenheap_mfn_start);
- vaddr = DIRECTMAP_VIRT_START + offset*PAGE_SIZE;
+ /*
+ * Virtual address aligned to previous 1GB to match physical
+ * address alignment done above.
+ */
+ vaddr = (vaddr_t)mfn_to_virt(base_mfn) & FIRST_MASK;
- while ( base_mfn < end_mfn )
+ while ( mfn < end_mfn )
{
int slot = zeroeth_table_offset(vaddr);
lpae_t *p = &xen_pgtable[slot];
@@ -716,11 +730,11 @@ void __init setup_xenheap_mappings(unsigned long base_mfn,
first = mfn_to_virt(first_mfn);
}
- pte = mfn_to_xen_entry(base_mfn, WRITEALLOC);
+ pte = mfn_to_xen_entry(mfn, WRITEALLOC);
/* TODO: Set pte.pt.contig when appropriate. */
write_pte(&first[first_table_offset(vaddr)], pte);
- base_mfn += FIRST_SIZE>>PAGE_SHIFT;
+ mfn += FIRST_SIZE>>PAGE_SHIFT;
vaddr += FIRST_SIZE;
}
diff --git a/xen/include/asm-arm/config.h b/xen/include/asm-arm/config.h
index 59b2887..264e2c1 100644
--- a/xen/include/asm-arm/config.h
+++ b/xen/include/asm-arm/config.h
@@ -162,7 +162,7 @@
#define DIRECTMAP_SIZE (SLOT0_ENTRY_SIZE * (265-256))
#define DIRECTMAP_VIRT_END (DIRECTMAP_VIRT_START + DIRECTMAP_SIZE - 1)
-#define XENHEAP_VIRT_START DIRECTMAP_VIRT_START
+#define XENHEAP_VIRT_START xenheap_virt_start
#define HYPERVISOR_VIRT_END DIRECTMAP_VIRT_END
diff --git a/xen/include/asm-arm/mm.h b/xen/include/asm-arm/mm.h
index 1e4711c..d25e485 100644
--- a/xen/include/asm-arm/mm.h
+++ b/xen/include/asm-arm/mm.h
@@ -110,7 +110,10 @@ struct page_info
#define PGC_count_mask ((1UL<<PGC_count_width)-1)
extern unsigned long xenheap_mfn_start, xenheap_mfn_end;
-extern unsigned long xenheap_virt_end;
+extern vaddr_t xenheap_virt_end;
+#ifdef CONFIG_ARM_64
+extern vaddr_t xenheap_virt_start;
+#endif
#ifdef CONFIG_ARM_32
#define is_xen_heap_page(page) is_xen_heap_mfn(page_to_mfn(page))
@@ -227,7 +230,7 @@ static inline void *maddr_to_virt(paddr_t ma)
static inline void *maddr_to_virt(paddr_t ma)
{
ASSERT(pfn_to_pdx(ma >> PAGE_SHIFT) < (DIRECTMAP_SIZE >> PAGE_SHIFT));
- return (void *)(DIRECTMAP_VIRT_START -
+ return (void *)(XENHEAP_VIRT_START -
pfn_to_paddr(xenheap_mfn_start) +
((ma & ma_va_bottom_mask) |
((ma & ma_top_mask) >> pfn_pdx_hole_shift)));
<Tested-by> Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
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