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KVM: emulate: clean up initializations in init_decode_cache
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A lot of initializations are unnecessary as they get set to
appropriate values before actually being used. Optimize
placement of fields in x86_emulate_ctxt

Signed-off-by: Bandan Das <bsd@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Bandan Das authored and Paolo Bonzini committed Jul 11, 2014
1 parent 02357bd commit c44b4c6
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Showing 2 changed files with 13 additions and 14 deletions.
20 changes: 11 additions & 9 deletions arch/x86/include/asm/kvm_emulate.h
Original file line number Diff line number Diff line change
Expand Up @@ -288,30 +288,32 @@ struct x86_emulate_ctxt {
u8 opcode_len;
u8 b;
u8 intercept;
u8 lock_prefix;
u8 rep_prefix;
u8 op_bytes;
u8 ad_bytes;
u8 rex_prefix;
struct operand src;
struct operand src2;
struct operand dst;
bool has_seg_override;
u8 seg_override;
u64 d;
int (*execute)(struct x86_emulate_ctxt *ctxt);
int (*check_perm)(struct x86_emulate_ctxt *ctxt);
bool has_seg_override;
bool rip_relative;
u8 rex_prefix;
u8 lock_prefix;
u8 rep_prefix;
u8 seg_override;
/* bitmaps of registers in _regs[] that can be read */
u32 regs_valid;
/* bitmaps of registers in _regs[] that have been written */
u32 regs_dirty;
/* modrm */
u8 modrm;
u8 modrm_mod;
u8 modrm_reg;
u8 modrm_rm;
u8 modrm_seg;
bool rip_relative;
u64 d;
unsigned long _eip;
struct operand memop;
u32 regs_valid; /* bitmaps of registers in _regs[] that can be read */
u32 regs_dirty; /* bitmaps of registers in _regs[] that have been written */
/* Fields above regs are cleared together. */
unsigned long _regs[NR_VCPU_REGS];
struct operand *memopp;
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7 changes: 2 additions & 5 deletions arch/x86/kvm/emulate.c
Original file line number Diff line number Diff line change
Expand Up @@ -4534,14 +4534,11 @@ static int fastop(struct x86_emulate_ctxt *ctxt, void (*fop)(struct fastop *))

void init_decode_cache(struct x86_emulate_ctxt *ctxt)
{
memset(&ctxt->opcode_len, 0,
(void *)&ctxt->_regs - (void *)&ctxt->opcode_len);
memset(&ctxt->has_seg_override, 0,
(void *)&ctxt->modrm - (void *)&ctxt->has_seg_override);

ctxt->fetch.start = 0;
ctxt->fetch.end = 0;
ctxt->io_read.pos = 0;
ctxt->io_read.end = 0;
ctxt->mem_read.pos = 0;
ctxt->mem_read.end = 0;
}

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