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Re: [Qemu-devel] [PATCH v2 06/10] target-mips: Set target page size to 1
From: |
Aurelien Jarno |
Subject: |
Re: [Qemu-devel] [PATCH v2 06/10] target-mips: Set target page size to 16K in KVM mode |
Date: |
Sat, 21 Dec 2013 16:34:22 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Mon, Dec 16, 2013 at 02:12:41PM +0000, James Hogan wrote:
> From: Sanjay Lal <address@hidden>
>
> With larger set associative caches KVM can open the possibility of cache
> aliasing between the memory that QEMU allocates with mmap and the
> mapping into the guest address space. Therefore increase the target page
> size to 16K when KVM is configured.
>
> Signed-off-by: Sanjay Lal <address@hidden>
> Signed-off-by: James Hogan <address@hidden>
> Cc: Aurelien Jarno <address@hidden>
> ---
> Changes in v2:
> - Expand commit message
> ---
> target-mips/mips-defs.h | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/target-mips/mips-defs.h b/target-mips/mips-defs.h
> index bf094a3..473ddf8 100644
> --- a/target-mips/mips-defs.h
> +++ b/target-mips/mips-defs.h
> @@ -5,7 +5,12 @@
> //#define USE_HOST_FLOAT_REGS
>
> /* Real pages are variable size... */
> +#ifdef CONFIG_KVM
> +/* For KVM/MIPS the minimum page size is 16K due to cache aliasing issues */
> +#define TARGET_PAGE_BITS 14
> +#else
> #define TARGET_PAGE_BITS 12
> +#endif
> #define MIPS_TLB_MAX 128
>
> #if defined(TARGET_MIPS64)
I am not sure it is something correct. It means that the emulated CPU
won't support 4K pages anymore, even when running in TCG mode without
KVM. If the kernel maps a 4K page, in practice a 16K page is going to be
mapped by the qemu tlb.
--
Aurelien Jarno GPG: 1024D/F1BCDB73
address@hidden http://www.aurel32.net
- Re: [Qemu-devel] [PATCH v2 05/10] kvm: Set sigmask length to 16 for MIPS targets, (continued)
- [Qemu-devel] [PATCH v2 08/10] hw/mips: In KVM mode, inject IRQ2 (I/O) interupts via ioctls, James Hogan, 2013/12/16
- [Qemu-devel] [PATCH v2 10/10] target-mips: Enable KVM support in build system, James Hogan, 2013/12/16
- [Qemu-devel] [PATCH v2 02/10] hw/mips: Add API to convert KVM guest KSEG0 <-> GPA, James Hogan, 2013/12/16
- [Qemu-devel] [PATCH v2 06/10] target-mips: Set target page size to 16K in KVM mode, James Hogan, 2013/12/16
- Re: [Qemu-devel] [PATCH v2 06/10] target-mips: Set target page size to 16K in KVM mode,
Aurelien Jarno <=
- [Qemu-devel] [PATCH v2 09/10] hw/mips: malta: Add KVM support, James Hogan, 2013/12/16
- [Qemu-devel] [PATCH v2 03/10] target-mips: get_physical_address: Add defines for segment bases, James Hogan, 2013/12/16
- [Qemu-devel] [PATCH v2 07/10] target-mips: kvm: Add main KVM support for MIPS, James Hogan, 2013/12/16
- [Qemu-devel] [PATCH v2 01/10] hw/mips/cputimer: Don't start periodic timer in KVM mode, James Hogan, 2013/12/16
- [Qemu-devel] [PATCH v2 04/10] target-mips: get_physical_address: Add KVM awareness, James Hogan, 2013/12/16