kvm: Allow to set shadow MMU size
Introduce the KVM-specific machine option kvm_shadow_mem. It allows to set a custom shadow MMU size for the virtual machine. This is useful for stress testing e.g. Only x86 supports this for now, but it is in principle a generic concept for all targets with shadow MMUs. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
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@ -535,6 +535,10 @@ static QemuOptsList qemu_machine_opts = {
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.name = "kernel_irqchip",
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.type = QEMU_OPT_BOOL,
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.help = "use KVM in-kernel irqchip",
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}, {
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.name = "kvm_shadow_mem",
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.type = QEMU_OPT_SIZE,
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.help = "KVM shadow MMU size",
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},
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{ /* End of list */ }
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},
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@ -32,7 +32,8 @@ DEF("machine", HAS_ARG, QEMU_OPTION_machine, \
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" selects emulated machine (-machine ? for list)\n"
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" property accel=accel1[:accel2[:...]] selects accelerator\n"
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" supported accelerators are kvm, xen, tcg (default: tcg)\n"
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" kernel_irqchip=on|off controls accelerated irqchip support\n",
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" kernel_irqchip=on|off controls accelerated irqchip support\n"
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" kvm_shadow_mem=size of KVM shadow MMU\n",
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QEMU_ARCH_ALL)
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STEXI
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@item -machine [type=]@var{name}[,prop=@var{value}[,...]]
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@ -47,6 +48,8 @@ than one accelerator specified, the next one is used if the previous one fails
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to initialize.
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@item kernel_irqchip=on|off
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Enables in-kernel irqchip support for the chosen accelerator when available.
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@item kvm_shadow_mem=size
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Defines the size of the KVM shadow MMU.
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@end table
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ETEXI
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@ -646,7 +646,9 @@ static int kvm_get_supported_msrs(KVMState *s)
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int kvm_arch_init(KVMState *s)
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{
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QemuOptsList *list = qemu_find_opts("machine");
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uint64_t identity_base = 0xfffbc000;
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uint64_t shadow_mem;
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int ret;
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struct utsname utsname;
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@ -693,6 +695,17 @@ int kvm_arch_init(KVMState *s)
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}
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qemu_register_reset(kvm_unpoison_all, NULL);
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if (!QTAILQ_EMPTY(&list->head)) {
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shadow_mem = qemu_opt_get_size(QTAILQ_FIRST(&list->head),
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"kvm_shadow_mem", -1);
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if (shadow_mem != -1) {
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shadow_mem /= 4096;
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ret = kvm_vm_ioctl(s, KVM_SET_NR_MMU_PAGES, shadow_mem);
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if (ret < 0) {
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return ret;
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}
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}
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}
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return 0;
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}
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