From: Paolo Bonzini <pbonzini@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: bdas@redhat.com, gleb@kernel.org
Subject: [PATCH 01/25] KVM: vmx: speed up emulation of invalid guest state
Date: Mon, 9 Jun 2014 14:58:49 +0200 [thread overview]
Message-ID: <1402318753-23362-2-git-send-email-pbonzini@redhat.com> (raw)
In-Reply-To: <1402318753-23362-1-git-send-email-pbonzini@redhat.com>
About 25% of the time spent in emulation of invalid guest state
is wasted in checking whether emulation is required for the next
instruction. However, this almost never changes except when a
segment register (or TR or LDTR) changes, or when there is a mode
transition (i.e. CR0 changes).
In fact, vmx_set_segment and vmx_set_cr0 already modify
vmx->emulation_required (except that the former for some reason
uses |= instead of just an assignment). So there is no need to
call guest_state_valid in the emulation loop.
Emulation performance test results indicate 1650-2600 cycles
for common instructions, versus 2300-3200 before this patch on
a Sandy Bridge Xeon.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/vmx.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 801332edefc3..a2ae11d162fe 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3653,7 +3653,7 @@ static void vmx_set_segment(struct kvm_vcpu *vcpu,
vmcs_write32(sf->ar_bytes, vmx_segment_access_rights(var));
out:
- vmx->emulation_required |= emulation_required(vcpu);
+ vmx->emulation_required = emulation_required(vcpu);
}
static void vmx_get_cs_db_l_bits(struct kvm_vcpu *vcpu, int *db, int *l)
@@ -5621,7 +5621,7 @@ static int handle_invalid_guest_state(struct kvm_vcpu *vcpu)
cpu_exec_ctrl = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL);
intr_window_requested = cpu_exec_ctrl & CPU_BASED_VIRTUAL_INTR_PENDING;
- while (!guest_state_valid(vcpu) && count-- != 0) {
+ while (vmx->emulation_required && count-- != 0) {
if (intr_window_requested && vmx_interrupt_allowed(vcpu))
return handle_interrupt_window(&vmx->vcpu);
@@ -5655,7 +5655,6 @@ static int handle_invalid_guest_state(struct kvm_vcpu *vcpu)
schedule();
}
- vmx->emulation_required = emulation_required(vcpu);
out:
return ret;
}
--
1.8.3.1
next prev parent reply other threads:[~2014-06-09 13:06 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 ` Paolo Bonzini [this message]
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 ` [PATCH 06/25] KVM: emulate: speed up emulated moves Paolo Bonzini
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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