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Re: [Qemu-devel] [PATCH] kvm-all: PAGE_SIZE should be real host page siz
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH] kvm-all: PAGE_SIZE should be real host page size |
Date: |
Tue, 10 Nov 2015 17:15:43 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 |
On 10/11/2015 16:57, Andrew Jones wrote:
> On Tue, Nov 10, 2015 at 04:41:16PM +0100, Paolo Bonzini wrote:
>>
>>
>> On 10/11/2015 01:23, Andrew Jones wrote:
>>> Just noticed this while grepping TARGET_PAGE_SIZE for an unrelated
>>> reason. I didn't use qemu_real_host_page_size as kvm_set_phys_mem()
>>> does, because we'd need to make sure page_size_init() has run first.
>>>
>>> Signed-off-by: Andrew Jones <address@hidden>
>>> ---
>>> kvm-all.c | 6 ++++--
>>> 1 file changed, 4 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/kvm-all.c b/kvm-all.c
>>> index 1bc12737723c3..de9ff5971fb3b 100644
>>> --- a/kvm-all.c
>>> +++ b/kvm-all.c
>>> @@ -45,8 +45,10 @@
>>> #include <sys/eventfd.h>
>>> #endif
>>>
>>> -/* KVM uses PAGE_SIZE in its definition of COALESCED_MMIO_MAX */
>>> -#define PAGE_SIZE TARGET_PAGE_SIZE
>>> +/* KVM uses PAGE_SIZE in its definition of KVM_COALESCED_MMIO_MAX. We
>>> + * need to use the real host PAGE_SIZE, as that's what KVM will use.
>>> + */
>>> +#define PAGE_SIZE getpagesize()
>>>
>>> //#define DEBUG_KVM
>>>
>>>
>>
>> Is this a bugfix or just a cleanup? If the former, on which targets?
>
> It's a bugfix for any targets that have a TARGET_PAGE_SIZE !=
> real-host-page-size. For example ARM has TARGET_PAGE_SIZE set to 1024,
> even when the host is using 4k or 64k pages. However, I didn't find this
> due to a bug, because on ARM I'm not using emulated devices that make
> use of the coalesced-mmio feature at this time.
>
> Thanks,
> drew
>
>>
>> Paolo
>> --
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Ok, applied (2.6 only unless I gather more urgent patches).
Paolo