126 lines
3.2 KiB
Plaintext
126 lines
3.2 KiB
Plaintext
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From: Alexander Graf <agraf@suse.de>
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Date: Wed, 18 Nov 2009 00:45:10 +0100
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Subject: Split the KVM pv-ops support by feature
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References: bnc#556135, FATE#306453
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Patch-Mainline: Submitted to virtualization list
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Currently selecting KVM guest support enabled multiple features at once that
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not everyone necessarily wants to have, namely:
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- PV MMU
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- zero io delay
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- apic detection workaround
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Let's split them off so we don't drag in the full pv-ops framework just to
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detect we're running on KVM. That gives us more chances to tweak performance!
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Signed-off-by: Alexander Graf <agraf@suse.de>
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---
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arch/x86/Kconfig | 29 ++++++++++++++++++++++++++++-
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arch/x86/kernel/kvm.c | 22 +++++++++++++++-------
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2 files changed, 43 insertions(+), 8 deletions(-)
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--- a/arch/x86/Kconfig
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+++ b/arch/x86/Kconfig
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@@ -539,11 +539,38 @@ config KVM_CLOCK
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config KVM_GUEST
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bool "KVM Guest support"
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- select PARAVIRT_ALL
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+ select PARAVIRT
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---help---
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This option enables various optimizations for running under the KVM
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hypervisor.
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+config KVM_IODELAY
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+ bool "KVM IO-delay support"
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+ depends on KVM_GUEST
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+ select PARAVIRT_CPU
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+ ---help---
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+ Usually we wait for PIO access to complete. When inside KVM there's
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+ no need to do that, as we know that we're not going through a bus,
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+ but process PIO requests instantly.
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+
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+ This option disables PIO waits, but drags in CPU-bound pv-ops. Thus
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+ you will probably get more speed loss than speedup using this option.
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+
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+ If in doubt, say N.
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+
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+config KVM_MMU
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+ bool "KVM PV MMU support"
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+ depends on KVM_GUEST
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+ select PARAVIRT_MMU
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+ ---help---
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+ This option enables the paravirtualized MMU for KVM. In most cases
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+ it's pretty useless and shouldn't be used.
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+
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+ It will only cost you performance, because it drags in pv-ops for
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+ memory management.
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+
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+ If in doubt, say N.
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+
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source "arch/x86/lguest/Kconfig"
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config PARAVIRT
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--- a/arch/x86/kernel/kvm.c
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+++ b/arch/x86/kernel/kvm.c
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@@ -29,6 +29,16 @@
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#include <linux/hardirq.h>
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#include <asm/timer.h>
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+#ifdef CONFIG_KVM_IODELAY
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+/*
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+ * No need for any "IO delay" on KVM
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+ */
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+static void kvm_io_delay(void)
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+{
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+}
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+#endif /* CONFIG_KVM_IODELAY */
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+
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+#ifdef CONFIG_KVM_MMU
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#define MMU_QUEUE_SIZE 1024
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struct kvm_para_state {
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@@ -43,13 +53,6 @@ static struct kvm_para_state *kvm_para_s
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return &per_cpu(para_state, raw_smp_processor_id());
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}
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-/*
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- * No need for any "IO delay" on KVM
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- */
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-static void kvm_io_delay(void)
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-{
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-}
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-
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static void kvm_mmu_op(void *buffer, unsigned len)
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{
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int r;
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@@ -194,15 +197,19 @@ static void kvm_leave_lazy_mmu(void)
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mmu_queue_flush(state);
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paravirt_leave_lazy_mmu();
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}
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+#endif /* CONFIG_KVM_MMU */
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static void __init paravirt_ops_setup(void)
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{
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pv_info.name = "KVM";
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pv_info.paravirt_enabled = 1;
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+#ifdef CONFIG_KVM_IODELAY
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if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY))
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pv_cpu_ops.io_delay = kvm_io_delay;
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+#endif
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+#ifdef CONFIG_KVM_MMU
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if (kvm_para_has_feature(KVM_FEATURE_MMU_OP)) {
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pv_mmu_ops.set_pte = kvm_set_pte;
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pv_mmu_ops.set_pte_at = kvm_set_pte_at;
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@@ -226,6 +233,7 @@ static void __init paravirt_ops_setup(vo
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pv_mmu_ops.lazy_mode.enter = kvm_enter_lazy_mmu;
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pv_mmu_ops.lazy_mode.leave = kvm_leave_lazy_mmu;
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}
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+#endif /* CONFIG_KVM_MMU */
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#ifdef CONFIG_X86_IO_APIC
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no_timer_check = 1;
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#endif
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