|
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen master] x86/shadow: avoid extra local array variable
commit 119f09734a75c65c3084eeff6698bb3f357b4f96
Author: Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Thu Mar 10 16:50:30 2016 +0100
Commit: Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Mar 10 16:50:30 2016 +0100
x86/shadow: avoid extra local array variable
mfns[2] was there just because struct sh_emulate_ctxt's two MFN values
can't be used to hand to vmap(). Making the structure fields an array
avoids the extra copying.
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Reviewed-by: Tim Deegan <tim@xxxxxxx>
---
xen/arch/x86/mm/shadow/common.c | 55 +++++++++++++++++++---------------------
xen/arch/x86/mm/shadow/multi.c | 4 +--
xen/arch/x86/mm/shadow/private.h | 2 +-
3 files changed, 29 insertions(+), 32 deletions(-)
diff --git a/xen/arch/x86/mm/shadow/common.c b/xen/arch/x86/mm/shadow/common.c
index fc1628b..ec87fb4 100644
--- a/xen/arch/x86/mm/shadow/common.c
+++ b/xen/arch/x86/mm/shadow/common.c
@@ -1746,11 +1746,11 @@ void *sh_emulate_map_dest(struct vcpu *v, unsigned long
vaddr,
struct domain *d = v->domain;
void *map;
- sh_ctxt->mfn1 = emulate_gva_to_mfn(v, vaddr, sh_ctxt);
- if ( !mfn_valid(sh_ctxt->mfn1) )
- return ((mfn_x(sh_ctxt->mfn1) == BAD_GVA_TO_GFN) ?
+ sh_ctxt->mfn[0] = emulate_gva_to_mfn(v, vaddr, sh_ctxt);
+ if ( !mfn_valid(sh_ctxt->mfn[0]) )
+ return ((mfn_x(sh_ctxt->mfn[0]) == BAD_GVA_TO_GFN) ?
MAPPING_EXCEPTION :
- (mfn_x(sh_ctxt->mfn1) == READONLY_GFN) ?
+ (mfn_x(sh_ctxt->mfn[0]) == READONLY_GFN) ?
MAPPING_SILENT_FAIL : MAPPING_UNHANDLEABLE);
#ifndef NDEBUG
@@ -1767,39 +1767,36 @@ void *sh_emulate_map_dest(struct vcpu *v, unsigned long
vaddr,
/* Unaligned writes mean probably this isn't a pagetable. */
if ( vaddr & (bytes - 1) )
- sh_remove_shadows(d, sh_ctxt->mfn1, 0, 0 /* Slow, can fail. */ );
+ sh_remove_shadows(d, sh_ctxt->mfn[0], 0, 0 /* Slow, can fail. */ );
if ( likely(((vaddr + bytes - 1) & PAGE_MASK) == (vaddr & PAGE_MASK)) )
{
/* Whole write fits on a single page. */
- sh_ctxt->mfn2 = _mfn(INVALID_MFN);
- map = map_domain_page(sh_ctxt->mfn1) + (vaddr & ~PAGE_MASK);
+ sh_ctxt->mfn[1] = _mfn(INVALID_MFN);
+ map = map_domain_page(sh_ctxt->mfn[0]) + (vaddr & ~PAGE_MASK);
}
- else
+ else if ( !is_hvm_domain(d) )
{
- mfn_t mfns[2];
-
/*
* Cross-page emulated writes are only supported for HVM guests;
* PV guests ought to know better.
*/
- if ( !is_hvm_domain(d) )
- return MAPPING_UNHANDLEABLE;
-
+ return MAPPING_UNHANDLEABLE;
+ }
+ else
+ {
/* This write crosses a page boundary. Translate the second page. */
- sh_ctxt->mfn2 = emulate_gva_to_mfn(v, vaddr + bytes - 1, sh_ctxt);
- if ( !mfn_valid(sh_ctxt->mfn2) )
- return ((mfn_x(sh_ctxt->mfn2) == BAD_GVA_TO_GFN) ?
+ sh_ctxt->mfn[1] = emulate_gva_to_mfn(v, vaddr + bytes - 1, sh_ctxt);
+ if ( !mfn_valid(sh_ctxt->mfn[1]) )
+ return ((mfn_x(sh_ctxt->mfn[1]) == BAD_GVA_TO_GFN) ?
MAPPING_EXCEPTION :
- (mfn_x(sh_ctxt->mfn2) == READONLY_GFN) ?
+ (mfn_x(sh_ctxt->mfn[1]) == READONLY_GFN) ?
MAPPING_SILENT_FAIL : MAPPING_UNHANDLEABLE);
/* Cross-page writes mean probably not a pagetable. */
- sh_remove_shadows(d, sh_ctxt->mfn2, 0, 0 /* Slow, can fail. */ );
+ sh_remove_shadows(d, sh_ctxt->mfn[1], 0, 0 /* Slow, can fail. */ );
- mfns[0] = sh_ctxt->mfn1;
- mfns[1] = sh_ctxt->mfn2;
- map = vmap(mfns, 2);
+ map = vmap(sh_ctxt->mfn, 2);
if ( !map )
return MAPPING_UNHANDLEABLE;
map += (vaddr & ~PAGE_MASK);
@@ -1831,7 +1828,7 @@ void sh_emulate_unmap_dest(struct vcpu *v, void *addr,
unsigned int bytes,
* - it was aligned to the PTE boundaries; and
* - _PAGE_PRESENT was clear before and after the write.
*/
- shflags = mfn_to_page(sh_ctxt->mfn1)->shadow_flags;
+ shflags = mfn_to_page(sh_ctxt->mfn[0])->shadow_flags;
#if (SHADOW_OPTIMIZATIONS & SHOPT_SKIP_VERIFY)
if ( sh_ctxt->low_bit_was_clear
&& !(*(u8 *)addr & _PAGE_PRESENT)
@@ -1852,12 +1849,12 @@ void sh_emulate_unmap_dest(struct vcpu *v, void *addr,
unsigned int bytes,
&& bytes <= 4)) )
{
/* Writes with this alignment constraint can't possibly cross pages. */
- ASSERT(!mfn_valid(sh_ctxt->mfn2));
+ ASSERT(!mfn_valid(sh_ctxt->mfn[1]));
}
else
#endif /* SHADOW_OPTIMIZATIONS & SHOPT_SKIP_VERIFY */
{
- if ( unlikely(mfn_valid(sh_ctxt->mfn2)) )
+ if ( unlikely(mfn_valid(sh_ctxt->mfn[1])) )
{
/* Validate as two writes, one to each page. */
b1 = PAGE_SIZE - (((unsigned long)addr) & ~PAGE_MASK);
@@ -1865,16 +1862,16 @@ void sh_emulate_unmap_dest(struct vcpu *v, void *addr,
unsigned int bytes,
ASSERT(b2 < bytes);
}
if ( likely(b1 > 0) )
- sh_validate_guest_pt_write(v, sh_ctxt->mfn1, addr, b1);
+ sh_validate_guest_pt_write(v, sh_ctxt->mfn[0], addr, b1);
if ( unlikely(b2 > 0) )
- sh_validate_guest_pt_write(v, sh_ctxt->mfn2, addr + b1, b2);
+ sh_validate_guest_pt_write(v, sh_ctxt->mfn[1], addr + b1, b2);
}
- paging_mark_dirty(v->domain, mfn_x(sh_ctxt->mfn1));
+ paging_mark_dirty(v->domain, mfn_x(sh_ctxt->mfn[0]));
- if ( unlikely(mfn_valid(sh_ctxt->mfn2)) )
+ if ( unlikely(mfn_valid(sh_ctxt->mfn[1])) )
{
- paging_mark_dirty(v->domain, mfn_x(sh_ctxt->mfn2));
+ paging_mark_dirty(v->domain, mfn_x(sh_ctxt->mfn[1]));
vunmap((void *)((unsigned long)addr & PAGE_MASK));
}
else
diff --git a/xen/arch/x86/mm/shadow/multi.c b/xen/arch/x86/mm/shadow/multi.c
index c334779..e5c8499 100644
--- a/xen/arch/x86/mm/shadow/multi.c
+++ b/xen/arch/x86/mm/shadow/multi.c
@@ -4615,13 +4615,13 @@ static void emulate_unmap_dest(struct vcpu *v,
u32 bytes,
struct sh_emulate_ctxt *sh_ctxt)
{
- ASSERT(mfn_valid(sh_ctxt->mfn1));
+ ASSERT(mfn_valid(sh_ctxt->mfn[0]));
/* If we are writing lots of PTE-aligned zeros, might want to unshadow */
if ( likely(bytes >= 4) && (*(u32 *)addr == 0) )
{
if ( ((unsigned long) addr & ((sizeof (guest_intpte_t)) - 1)) == 0 )
- check_for_early_unshadow(v, sh_ctxt->mfn1);
+ check_for_early_unshadow(v, sh_ctxt->mfn[0]);
/* Don't reset the heuristic if we're writing zeros at non-aligned
* addresses, otherwise it doesn't catch REP MOVSD on PAE guests */
}
diff --git a/xen/arch/x86/mm/shadow/private.h b/xen/arch/x86/mm/shadow/private.h
index e061cbb..c424ad6 100644
--- a/xen/arch/x86/mm/shadow/private.h
+++ b/xen/arch/x86/mm/shadow/private.h
@@ -727,7 +727,7 @@ struct sh_emulate_ctxt {
struct segment_register seg_reg[6];
/* MFNs being written to in write/cmpxchg callbacks */
- mfn_t mfn1, mfn2;
+ mfn_t mfn[2];
#if (SHADOW_OPTIMIZATIONS & SHOPT_SKIP_VERIFY)
/* Special case for avoiding having to verify writes: remember
--
generated by git-patchbot for /home/xen/git/xen.git#master
_______________________________________________
Xen-changelog mailing list
Xen-changelog@xxxxxxxxxxxxx
http://lists.xensource.com/xen-changelog
|
 |
Lists.xenproject.org is hosted with RackSpace, monitoring our |