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Re: [Qemu-devel] [PATCH 28/31] vga: disable chain4_alias if KVM supports
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH 28/31] vga: disable chain4_alias if KVM supports SMRAM |
Date: |
Tue, 19 May 2015 13:51:23 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 |
This actually is not needed anymore in the latest incarnation of the
kernel-side interface.
Paolo
On 11/05/2015 15:49, Paolo Bonzini wrote:
> KVM is okay with SMRAM overlapping an MMIO area underneath it, but it does
> not want to have two overlapping RAM slots for SMRAM and video RAM.
> Unfortunately, the chain4_alias optimization results in the latter
> situation. Disable it if KVM supports system management mode.
>
> Note that the chain4_alias optimization is misguided, because it assumes
> that chain4 data is at VRAM address 0,1,2,3,4,5,6,7...16383. This is
> incorrect, because chain4 data is at VRAM address 0,1,2,3, 16,17,18,19,
> ..., 65523. But we cannot fix the VRAM format without breaking migration,
> so keep the optimization and just disable it if it gets in the way.
>
> Signed-off-by: Paolo Bonzini <address@hidden>
> ---
> hw/display/vga.c | 8 ++++++--
> hw/display/vga_int.h | 1 +
> include/sysemu/kvm.h | 1 +
> kvm-all.c | 5 +++++
> kvm-stub.c | 5 +++++
> 5 files changed, 18 insertions(+), 2 deletions(-)
>
> diff --git a/hw/display/vga.c b/hw/display/vga.c
> index d1d296c..b1925a0 100644
> --- a/hw/display/vga.c
> +++ b/hw/display/vga.c
> @@ -154,7 +154,8 @@ static void vga_update_memory_access(VGACommonState *s)
> s->has_chain4_alias = false;
> s->plane_updated = 0xf;
> }
> - if ((s->sr[VGA_SEQ_PLANE_WRITE] & VGA_SR02_ALL_PLANES) ==
> + if (s->use_chain4_alias &&
> + (s->sr[VGA_SEQ_PLANE_WRITE] & VGA_SR02_ALL_PLANES) ==
> VGA_SR02_ALL_PLANES && s->sr[VGA_SEQ_MEMORY_MODE] & VGA_SR04_CHN_4M)
> {
> offset = 0;
> switch ((s->gr[VGA_GFX_MISC] >> 2) & 3) {
> @@ -2219,8 +2220,11 @@ void vga_init(VGACommonState *s, Object *obj,
> MemoryRegion *address_space,
>
> qemu_register_reset(vga_reset, s);
>
> - s->bank_offset = 0;
> + if (!kvm_enabled() || !kvm_has_smm()) {
> + s->use_chain4_alias = true;
> + }
>
> + s->bank_offset = 0;
> s->legacy_address_space = address_space;
>
> vga_io_memory = vga_init_io(s, obj, &vga_ports, &vbe_ports);
> diff --git a/hw/display/vga_int.h b/hw/display/vga_int.h
> index fcfcc5f..646e64c 100644
> --- a/hw/display/vga_int.h
> +++ b/hw/display/vga_int.h
> @@ -95,6 +95,7 @@ typedef struct VGACommonState {
> uint32_t vram_size_mb; /* property */
> uint32_t vbe_size;
> uint32_t latch;
> + bool use_chain4_alias;
> bool has_chain4_alias;
> MemoryRegion chain4_alias;
> uint8_t sr_index;
> diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
> index 4878959..e1db979 100644
> --- a/include/sysemu/kvm.h
> +++ b/include/sysemu/kvm.h
> @@ -186,6 +186,7 @@ int kvm_has_pit_state2(void);
> int kvm_has_many_ioeventfds(void);
> int kvm_has_gsi_routing(void);
> int kvm_has_intx_set_mask(void);
> +int kvm_has_smm(void);
>
> int kvm_init_vcpu(CPUState *cpu);
> int kvm_cpu_exec(CPUState *cpu);
> diff --git a/kvm-all.c b/kvm-all.c
> index 17a3771..5ad4877 100644
> --- a/kvm-all.c
> +++ b/kvm-all.c
> @@ -1990,6 +1990,11 @@ int kvm_vm_check_attr(KVMState *s, uint32_t group,
> uint64_t attr)
> return ret ? 0 : 1;
> }
>
> +int kvm_has_smm(void)
> +{
> + return kvm_check_extension(kvm_state, KVM_CAP_X86_SMM);
> +}
> +
> int kvm_has_sync_mmu(void)
> {
> return kvm_check_extension(kvm_state, KVM_CAP_SYNC_MMU);
> diff --git a/kvm-stub.c b/kvm-stub.c
> index 7ba90c5..c3428a5 100644
> --- a/kvm-stub.c
> +++ b/kvm-stub.c
> @@ -56,6 +56,11 @@ int kvm_cpu_exec(CPUState *cpu)
> abort();
> }
>
> +int kvm_has_smm(void)
> +{
> + return 0;
> +}
> +
> int kvm_has_sync_mmu(void)
> {
> return 0;
>
[Qemu-devel] [PATCH 24/31] hw/acpi: acpi_pm1_cnt_init(): take "disable_s3" and "disable_s4", Paolo Bonzini, 2015/05/11
[Qemu-devel] [PATCH 25/31] hw/acpi: move "etc/system-states" fw_cfg file from PIIX4 to core, Paolo Bonzini, 2015/05/11
[Qemu-devel] [PATCH 26/31] hw/acpi: piix4_pm_init(): take fw_cfg object no more, Paolo Bonzini, 2015/05/11
[Qemu-devel] [PATCH 28/31] vga: disable chain4_alias if KVM supports SMRAM, Paolo Bonzini, 2015/05/11
- Re: [Qemu-devel] [PATCH 28/31] vga: disable chain4_alias if KVM supports SMRAM,
Paolo Bonzini <=
[Qemu-devel] [PATCH 29/31] pc_piix: rename kvm_enabled to smm_enabled, Paolo Bonzini, 2015/05/11
[Qemu-devel] [PATCH 27/31] target-i386: add support for SMBASE MSR and SMIs, Paolo Bonzini, 2015/05/11
[Qemu-devel] [PATCH 31/31] pc: add SMM property, Paolo Bonzini, 2015/05/11
[Qemu-devel] [PATCH 30/31] ich9: add smm_enabled field and arguments, Paolo Bonzini, 2015/05/11
Message not available
Re: [Qemu-devel] [PATCH 00/31] target-i386: SMM improvements and partial support under KVM, Michael S. Tsirkin, 2015/05/31