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[Qemu-devel] Re: [PATCH 7/7] Fake dirty loggin when it's not there
From: |
Jan Kiszka |
Subject: |
[Qemu-devel] Re: [PATCH 7/7] Fake dirty loggin when it's not there |
Date: |
Fri, 17 Jul 2009 17:47:53 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
Alexander Graf wrote:
>
> On 17.07.2009, at 16:37, Jan Kiszka wrote:
>
>> Alexander Graf wrote:
>>> Some KVM platforms don't support dirty logging yet, like IA64 and PPC,
>>> so in order to still have screen updates on those, we need to fake it.
>>>
>>> This patch just tells the getter function for dirty bitmaps, that all
>>> pages within a slot are dirty when the slot has dirty logging enabled.
>>>
>>> That way we can implement dirty logging on those platforms sometime when
>>> it drags down performance, but share the rest of the code with dirty
>>> logging capable platforms.
>>>
>>> Signed-off-by: Alexander Graf <address@hidden>
>>> ---
>>> kvm-all.c | 13 ++++++++++++-
>>> 1 files changed, 12 insertions(+), 1 deletions(-)
>>>
>>> diff --git a/kvm-all.c b/kvm-all.c
>>> index 60b76cf..72b7935 100644
>>> --- a/kvm-all.c
>>> +++ b/kvm-all.c
>>> @@ -300,6 +300,7 @@ int
>>> kvm_physical_sync_dirty_bitmap(target_phys_addr_t start_addr,
>>> KVMDirtyLog d;
>>> KVMSlot *mem;
>>> int ret = 0;
>>> + int r;
>>>
>>> d.dirty_bitmap = NULL;
>>> while (start_addr < end_addr) {
>>> @@ -308,6 +309,11 @@ int
>>> kvm_physical_sync_dirty_bitmap(target_phys_addr_t start_addr,
>>> break;
>>> }
>>>
>>> + /* We didn't activate dirty logging? Don't care then. */
>>> + if(!(mem->flags & KVM_MEM_LOG_DIRTY_PAGES)) {
>>> + continue;
>>> + }
>>> +
>>
>> Isn't this worth a separate patch? Do we already run into this patch on
>> dirty-logging archs (ie. x86)? I'm still wondering why it's needed.
>
> We don't. I'm just being paranoid.
>
>>> size = ((mem->memory_size >> TARGET_PAGE_BITS) + 7) / 8;
>>> if (!d.dirty_bitmap) {
>>> d.dirty_bitmap = qemu_malloc(size);
>>> @@ -319,7 +325,8 @@ int
>>> kvm_physical_sync_dirty_bitmap(target_phys_addr_t start_addr,
>>>
>>> d.slot = mem->slot;
>>>
>>> - if (kvm_vm_ioctl(s, KVM_GET_DIRTY_LOG, &d) == -1) {
>>> + r = kvm_vm_ioctl(s, KVM_GET_DIRTY_LOG, &d);
>>> + if (r == -EINVAL) {
>>
>> I would say, better exclude 0 and the error you for missing support here
>> than to assume only EINVAL is a "real" error.
>
> Hum, this was the logic that was there before and it makes sense.
> -EINVAL is used for errors whole -ENOTSUPP is used for N/A.
> Unfortunately -ENOTSUPP is only exported when __KERNEL__ is defined.
Uuh, kvm returns a private error code to user space? That would be a
bug. So we need a check for the to-be-fixed error code and >= 512.
Jan
--
Siemens AG, Corporate Technology, CT SE 2
Corporate Competence Center Embedded Linux
- [Qemu-devel] [PATCH 7/7] Fake dirty loggin when it's not there, (continued)
- [Qemu-devel] [PATCH 7/7] Fake dirty loggin when it's not there, Alexander Graf, 2009/07/17
- Re: [Qemu-devel] [PATCH 7/7] Fake dirty loggin when it's not there, Stefano Stabellini, 2009/07/17
- Re: [Qemu-devel] [PATCH 7/7] Fake dirty loggin when it's not there, Alexander Graf, 2009/07/17
- Re: [Qemu-devel] [PATCH 7/7] Fake dirty loggin when it's not there, Alexander Graf, 2009/07/17
- Re: [Qemu-devel] [PATCH 7/7] Fake dirty loggin when it's not there, Stefano Stabellini, 2009/07/17
- Re: [Qemu-devel] [PATCH 7/7] Fake dirty loggin when it's not there, Alexander Graf, 2009/07/17
- Re: [Qemu-devel] [PATCH 7/7] Fake dirty loggin when it's not there, Stefano Stabellini, 2009/07/17
- Re: [Qemu-devel] [PATCH 7/7] Fake dirty loggin when it's not there, Alexander Graf, 2009/07/17
- [Qemu-devel] Re: [PATCH 7/7] Fake dirty loggin when it's not there, Jan Kiszka, 2009/07/17
- [Qemu-devel] Re: [PATCH 7/7] Fake dirty loggin when it's not there, Alexander Graf, 2009/07/17
- [Qemu-devel] Re: [PATCH 7/7] Fake dirty loggin when it's not there,
Jan Kiszka <=
- [Qemu-devel] Re: [PATCH 6/7] Set slots more carefully, Jan Kiszka, 2009/07/17
- [Qemu-devel] Re: [PATCH 6/7] Set slots more carefully, Alexander Graf, 2009/07/17
- [Qemu-devel] Re: [PATCH 6/7] Set slots more carefully, Jan Kiszka, 2009/07/17
- [Qemu-devel] Re: [PATCH 6/7] Set slots more carefully, Alexander Graf, 2009/07/17
- [Qemu-devel] Re: [PATCH 6/7] Set slots more carefully, Jan Kiszka, 2009/07/17
- Re: [Qemu-devel] [PATCH 6/7] Set slots more carefully, Anthony Liguori, 2009/07/21
- Re: [Qemu-devel] [PATCH 3/7] Add mp_state to PPC CPU struct, Anthony Liguori, 2009/07/22
- Re: [Qemu-devel] [PATCH 3/7] Add mp_state to PPC CPU struct, Hollis Blanchard, 2009/07/22
- Re: [Qemu-devel] [PATCH 3/7] Add mp_state to PPC CPU struct, Anthony Liguori, 2009/07/22
- Re: [Qemu-devel] [PATCH 3/7] Add mp_state to PPC CPU struct, Hollis Blanchard, 2009/07/22