From: Paolo Bonzini <pbonzini@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: bdas@redhat.com, gleb@kernel.org
Subject: [PATCH 06/25] KVM: emulate: speed up emulated moves
Date: Mon, 9 Jun 2014 14:58:54 +0200 [thread overview]
Message-ID: <1402318753-23362-7-git-send-email-pbonzini@redhat.com> (raw)
In-Reply-To: <1402318753-23362-1-git-send-email-pbonzini@redhat.com>
We can just blindly move all 16 bytes of ctxt->src's value to ctxt->dst.
write_register_operand will take care of writing only the lower bytes.
Avoiding a call to memcpy (the compiler optimizes it out) gains about
200 cycles on kvm-unit-tests for register-to-register moves, and makes
them about as fast as arithmetic instructions.
We could perhaps get a larger speedup by moving all instructions _except_
moves out of x86_emulate_insn, removing opcode_len, and replacing the
switch statement with an inlined em_mov.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/include/asm/kvm_emulate.h | 2 +-
arch/x86/kvm/emulate.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index ffa2671a7f2f..46725e8aa8cb 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -232,7 +232,7 @@ struct operand {
union {
unsigned long val;
u64 val64;
- char valptr[sizeof(unsigned long) + 2];
+ char valptr[sizeof(sse128_t)];
sse128_t vec_val;
u64 mm_val;
void *data;
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 4c2ae824e89e..5f902d40740c 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2983,7 +2983,7 @@ static int em_rdpmc(struct x86_emulate_ctxt *ctxt)
static int em_mov(struct x86_emulate_ctxt *ctxt)
{
- memcpy(ctxt->dst.valptr, ctxt->src.valptr, ctxt->op_bytes);
+ memcpy(ctxt->dst.valptr, ctxt->src.valptr, sizeof(ctxt->src.valptr));
return X86EMUL_CONTINUE;
}
--
1.8.3.1
next prev parent reply other threads:[~2014-06-09 12:59 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-09 12:58 [PATCH 00/25] KVM: x86: Speed up emulation of invalid state Paolo Bonzini
2014-06-09 12:58 ` [PATCH 01/25] KVM: vmx: speed up emulation of invalid guest state Paolo Bonzini
2014-06-09 12:58 ` [PATCH 02/25] KVM: x86: return all bits from get_interrupt_shadow Paolo Bonzini
2014-06-09 12:58 ` [PATCH 03/25] KVM: x86: avoid useless set of KVM_REQ_EVENT after emulation Paolo Bonzini
2014-06-09 12:58 ` [PATCH 04/25] KVM: emulate: move around some checks Paolo Bonzini
2014-06-09 12:58 ` [PATCH 05/25] KVM: emulate: protect checks on ctxt->d by a common "if (unlikely())" Paolo Bonzini
2014-06-09 12:58 ` Paolo Bonzini [this message]
2014-06-09 12:58 ` [PATCH 07/25] KVM: emulate: simplify writeback Paolo Bonzini
2014-06-09 12:58 ` [PATCH 08/25] KVM: emulate: abstract handling of memory operands Paolo Bonzini
2014-06-09 12:58 ` [PATCH 09/25] KVM: export mark_page_dirty_in_slot Paolo Bonzini
2014-06-09 12:58 ` [PATCH 10/25] KVM: emulate: introduce memory_prepare callback to speed up memory access Paolo Bonzini
2014-06-09 12:58 ` [PATCH 11/25] KVM: emulate: activate memory access optimization Paolo Bonzini
2014-06-09 12:59 ` [PATCH 12/25] KVM: emulate: extend memory access optimization to stores Paolo Bonzini
2014-06-09 18:40 ` Bandan Das
2014-06-19 11:37 ` Paolo Bonzini
2014-06-09 12:59 ` [PATCH 13/25] KVM: emulate: move init_decode_cache to emulate.c Paolo Bonzini
2014-06-09 12:59 ` [PATCH 14/25] KVM: emulate: Remove ctxt->intercept and ctxt->check_perm checks Paolo Bonzini
2014-06-09 12:59 ` [PATCH 15/25] KVM: emulate: cleanup decode_modrm Paolo Bonzini
2014-06-09 12:59 ` [PATCH 16/25] KVM: emulate: clean up initializations in init_decode_cache Paolo Bonzini
2014-06-09 12:59 ` [PATCH 17/25] KVM: emulate: rework seg_override Paolo Bonzini
2014-06-09 12:59 ` [PATCH 18/25] KVM: emulate: do not initialize memopp Paolo Bonzini
2014-06-09 12:59 ` [PATCH 19/25] KVM: emulate: speed up do_insn_fetch Paolo Bonzini
2014-06-09 12:59 ` [PATCH 20/25] KVM: emulate: avoid repeated calls to do_insn_fetch_bytes Paolo Bonzini
2014-06-09 12:59 ` [PATCH 21/25] KVM: emulate: avoid per-byte copying in instruction fetches Paolo Bonzini
2014-06-09 12:59 ` [PATCH 22/25] KVM: emulate: put pointers in the fetch_cache Paolo Bonzini
2014-06-09 12:59 ` [PATCH 23/25] KVM: x86: use kvm_read_guest_page for emulator accesses Paolo Bonzini
2014-06-09 12:59 ` [PATCH 24/25] KVM: emulate: simplify BitOp handling Paolo Bonzini
2014-06-09 12:59 ` [PATCH 25/25] KVM: emulate: fix harmless typo in MMX decoding Paolo Bonzini
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