From ba6059b08219ec841fac95e1a4d067dd1d22f08f Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Fri, 20 Sep 2013 11:05:28 +0200 Subject: [PATCH] x86_emulate: fold wide reads With HVM's MMIO operand handling now being capable of splitting large reads, there's no need to issue at most machine word size reads when we really need wider operands. Not that this is not done everywhere - there are a couple of cases where keeping the reads separate is more natural (and folding them would complicate the code rather than simplifying it). Signed-off-by: Jan Beulich Acked-by: Keir Fraser --- xen/arch/x86/x86_emulate/x86_emulate.c | 18 +++++------------- 1 file changed, 5 insertions(+), 13 deletions(-) diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c b/xen/arch/x86/x86_emulate/x86_emulate.c index d3023de0eb..473500ec04 100644 --- a/xen/arch/x86/x86_emulate/x86_emulate.c +++ b/xen/arch/x86/x86_emulate/x86_emulate.c @@ -1116,7 +1116,6 @@ protmode_load_seg( { struct segment_register desctab, ss, segr; struct { uint32_t a, b; } desc; - unsigned long val; uint8_t dpl, rpl, cpl; uint32_t new_desc_b, a_flag = 0x100; int rc, fault_type = EXC_GP; @@ -1143,14 +1142,9 @@ protmode_load_seg( if ( ((sel & 0xfff8) + 7) > desctab.limit ) goto raise_exn; - if ( (rc = read_ulong(x86_seg_none, desctab.base + (sel & 0xfff8), - &val, 4, ctxt, ops)) ) + if ( (rc = ops->read(x86_seg_none, desctab.base + (sel & 0xfff8), + &desc, sizeof(desc), ctxt)) ) return rc; - desc.a = val; - if ( (rc = read_ulong(x86_seg_none, desctab.base + (sel & 0xfff8) + 4, - &val, 4, ctxt, ops)) ) - return rc; - desc.b = val; /* Segment present in memory? */ if ( !(desc.b & (1u<<15)) ) @@ -4454,7 +4448,6 @@ x86_emulate( case 0xc7: /* Grp9 (cmpxchg8b/cmpxchg16b) */ { unsigned long old[2], exp[2], new[2]; - unsigned int i; generate_exception_if((modrm_reg & 7) != 1, EXC_UD, -1); generate_exception_if(ea.type != OP_MEM, EXC_UD, -1); @@ -4463,10 +4456,9 @@ x86_emulate( op_bytes *= 2; /* Get actual old value. */ - for ( i = 0; i < (op_bytes/sizeof(long)); i++ ) - if ( (rc = read_ulong(ea.mem.seg, ea.mem.off + i*sizeof(long), - &old[i], sizeof(long), ctxt, ops)) != 0 ) - goto done; + if ( (rc = ops->read(ea.mem.seg, ea.mem.off, old, op_bytes, + ctxt)) != 0 ) + goto done; /* Get expected and proposed values. */ if ( op_bytes == 8 ) -- 2.30.2