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Commit dd856efa authored by Avi Kivity's avatar Avi Kivity Committed by Marcelo Tosatti
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KVM: x86 emulator: access GPRs on demand 



Instead of populating the entire register file, read in registers
as they are accessed, and write back only the modified ones.  This
saves a VMREAD and VMWRITE on Intel (for rsp, since it is not usually
used during emulation), and a two 128-byte copies for the registers.

Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent 66a03505

arch/x86/include/asm/kvm_emulate.h

+19 −1
Original line number Diff line number Diff line
@@ -85,6 +85,19 @@ struct x86_instruction_info { 
#define X86EMUL_INTERCEPTED     6 /* Intercepted by nested VMCB/VMCS */



struct x86_emulate_ops {

	/*

	 * read_gpr: read a general purpose register (rax - r15)

	 *

	 * @reg: gpr number.

	 */

	ulong (*read_gpr)(struct x86_emulate_ctxt *ctxt, unsigned reg);

	/*

	 * write_gpr: write a general purpose register (rax - r15)

	 *

	 * @reg: gpr number.

	 * @val: value to write.

	 */

	void (*write_gpr)(struct x86_emulate_ctxt *ctxt, unsigned reg, ulong val);

	/*

	 * read_std: Read bytes of standard (non-emulated/special) memory.

	 *           Used for descriptor reading.
@@ -281,8 +294,10 @@ struct x86_emulate_ctxt { 
	bool rip_relative;

	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];

	unsigned long _regs[NR_VCPU_REGS];

	struct operand *memopp;

	struct fetch_cache fetch;

	struct read_cache io_read;
@@ -394,4 +409,7 @@ int emulator_task_switch(struct x86_emulate_ctxt *ctxt, 
			 u16 tss_selector, int idt_index, int reason,

			 bool has_error_code, u32 error_code);

int emulate_int_real(struct x86_emulate_ctxt *ctxt, int irq);

void emulator_invalidate_register_cache(struct x86_emulate_ctxt *ctxt);

void emulator_writeback_register_cache(struct x86_emulate_ctxt *ctxt);



#endif /* _ASM_X86_KVM_X86_EMULATE_H */

arch/x86/kvm/emulate.c

+183 −116

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arch/x86/kvm/x86.c

+18 −27

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