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Re: [Qemu-devel] [PATCH] qemu: enable PV EOI for qemu 1.3
From: |
Eduardo Habkost |
Subject: |
Re: [Qemu-devel] [PATCH] qemu: enable PV EOI for qemu 1.3 |
Date: |
Wed, 17 Oct 2012 17:03:02 -0300 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Wed, Oct 17, 2012 at 09:40:59PM +0200, Michael S. Tsirkin wrote:
> Enable KVM PV EOI by default. You can still disable it with
> -kvm_pv_eoi cpu flag. To avoid breaking cross-version migration,
> enable only for qemu 1.3 or newer machine type.
>
> Signed-off-by: Michael S. Tsirkin <address@hidden>
> ---
> hw/pc.h | 2 ++
> hw/pc_piix.c | 14 +++++++++++++-
> target-i386/cpu.c | 15 +++++++++++++++
> 3 files changed, 30 insertions(+), 1 deletion(-)
>
> diff --git a/hw/pc.h b/hw/pc.h
> index 9923d96..344a545 100644
> --- a/hw/pc.h
> +++ b/hw/pc.h
> @@ -210,4 +210,6 @@ void pc_system_firmware_init(MemoryRegion *rom_memory);
>
> int e820_add_entry(uint64_t, uint64_t, uint32_t);
>
> +void enable_kvm_pv_eoi(void);
> +
> #endif
> diff --git a/hw/pc_piix.c b/hw/pc_piix.c
> index 82364ab..9d4cf48 100644
> --- a/hw/pc_piix.c
> +++ b/hw/pc_piix.c
> @@ -301,6 +301,18 @@ static void pc_init_pci(ram_addr_t ram_size,
> initrd_filename, cpu_model, 1, 1);
> }
>
> +static void pc_init_pci_pv_eoi(ram_addr_t ram_size,
> + const char *boot_device,
> + const char *kernel_filename,
> + const char *kernel_cmdline,
> + const char *initrd_filename,
> + const char *cpu_model)
> +{
> + enable_kvm_pv_eoi();
> + pc_init_pci(ram_size, boot_device, kernel_filename,
> + kernel_cmdline, initrd_filename, cpu_model);
> +}
Maybe it's better to name it pc_init_pci_1_3() (or something like that)?
I plan to submit a bug fix (unrelated to PV EOI) that will require using
a separate init function for the pc-1.3 machine type too, so pv_eoi
won't be the only difference between pc-1.2 and pc-1.3.
> +
> static void pc_init_pci_no_kvmclock(ram_addr_t ram_size,
> const char *boot_device,
> const char *kernel_filename,
> @@ -353,7 +365,7 @@ static QEMUMachine pc_machine_v1_3 = {
> .name = "pc-1.3",
> .alias = "pc",
> .desc = "Standard PC",
> - .init = pc_init_pci,
> + .init = pc_init_pci_pv_eoi,
> .max_cpus = 255,
> .is_default = 1,
> };
> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> index f3708e6..a4a8a02 100644
> --- a/target-i386/cpu.c
> +++ b/target-i386/cpu.c
> @@ -1097,6 +1097,8 @@ static void x86_cpuid_set_tsc_freq(Object *obj, Visitor
> *v, void *opaque,
> cpu->env.tsc_khz = value / 1000;
> }
>
> +static bool kvm_pv_eoi_enabled;
Maybe we can do this as:
static int default_kvm_features = (1 << KVM_FEATURE_CLOCKSOURCE) |
(1 << KVM_FEATURE_NOP_IO_DELAY) |
(1 << KVM_FEATURE_MMU_OP) |
(1 << KVM_FEATURE_CLOCKSOURCE2) |
(1 << KVM_FEATURE_ASYNC_PF) |
(1 << KVM_FEATURE_STEAL_TIME) |
(1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT);
[...]
static int cpu_x86_find_by_name(x86_def_t *x86_cpu_def, const char *cpu_model)
{
[...]
plus_kvm_features = default_kvm_features;
[...]
}
[...]
void enable_kvm_pv_eoi(void)
{
default_kvm_features = (1UL << KVM_FEATURE_PV_EOI);
}
On either case, the global variable should eventually go away when we
make CPU objects support global properties. But I still support
including a solution like this one, as the CPU modelling work is taking
really long to be finished and I don't think this should hold the
inclusion of pv_eoi support.
> +
> static int cpu_x86_find_by_name(x86_def_t *x86_cpu_def, const char
> *cpu_model)
> {
> unsigned int i;
> @@ -1135,6 +1137,8 @@ static int cpu_x86_find_by_name(x86_def_t *x86_cpu_def,
> const char *cpu_model)
> (1 << KVM_FEATURE_ASYNC_PF) |
> (1 << KVM_FEATURE_STEAL_TIME) |
> (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT);
> + if (kvm_pv_eoi_enabled)
> + plus_kvm_features |= (0x1 << KVM_FEATURE_PV_EOI);
> #else
> plus_kvm_features = 0;
> #endif
> @@ -1953,3 +1957,14 @@ static void x86_cpu_register_types(void)
> }
>
> type_init(x86_cpu_register_types)
> +
> +/* Called from hw/pc_piix.c but there is no header
> + * both files include to put this into.
> + * Put it here to silence compiler warning.
> + */
Why can't pc_piix.c simply include cpu.h?
> +void enable_kvm_pv_eoi(void);
> +
> +void enable_kvm_pv_eoi(void)
> +{
> + kvm_pv_eoi_enabled = true;
> +}
> --
> MST
--
Eduardo