> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On
> Behalf Of "“tiejun.chen”"
> Sent: Thursday, July 18, 2013 1:01 PM
> To: Bhushan Bharat-R65777
> Cc: [email protected]; [email protected]; [email protected]; Wood Scott-
> B07421
> Subject: Re: [PATCH 2/2] kvm: powerpc: set cache coherency only for kernel
> managed pages
>
> On 07/18/2013 03:12 PM, Bhushan Bharat-R65777 wrote:
> >
> >
> >> -----Original Message-----
> >> From: "“tiejun.chen”" [mailto:[email protected]]
> >> Sent: Thursday, July 18, 2013 11:56 AM
> >> To: Bhushan Bharat-R65777
> >> Cc: [email protected]; [email protected]; [email protected]; Wood
> >> Scott- B07421; Bhushan Bharat-R65777
> >> Subject: Re: [PATCH 2/2] kvm: powerpc: set cache coherency only for
> >> kernel managed pages
> >>
> >> On 07/18/2013 02:04 PM, Bharat Bhushan wrote:
> >>> If there is a struct page for the requested mapping then it's normal
> >>> DDR and the mapping sets "M" bit (coherent, cacheable) else this is
> >>> treated as I/O and we set "I + G" (cache inhibited, guarded)
> >>>
> >>> This helps setting proper TLB mapping for direct assigned device
> >>>
> >>> Signed-off-by: Bharat Bhushan <[email protected]>
> >>> ---
> >>> arch/powerpc/kvm/e500_mmu_host.c | 17 ++++++++++++-----
> >>> 1 files changed, 12 insertions(+), 5 deletions(-)
> >>>
> >>> diff --git a/arch/powerpc/kvm/e500_mmu_host.c
> >>> b/arch/powerpc/kvm/e500_mmu_host.c
> >>> index 1c6a9d7..089c227 100644
> >>> --- a/arch/powerpc/kvm/e500_mmu_host.c
> >>> +++ b/arch/powerpc/kvm/e500_mmu_host.c
> >>> @@ -64,13 +64,20 @@ static inline u32 e500_shadow_mas3_attrib(u32
> >>> mas3, int
> >> usermode)
> >>> return mas3;
> >>> }
> >>>
> >>> -static inline u32 e500_shadow_mas2_attrib(u32 mas2, int usermode)
> >>> +static inline u32 e500_shadow_mas2_attrib(u32 mas2, pfn_t pfn)
> >>> {
> >>> + u32 mas2_attr;
> >>> +
> >>> + mas2_attr = mas2 & MAS2_ATTRIB_MASK;
> >>> +
> >>> + if (!pfn_valid(pfn)) {
> >>
> >> Why not directly use kvm_is_mmio_pfn()?
> >
> > What I understand from this function (someone can correct me) is that it
> returns "false" when the page is managed by kernel and is not marked as
> RESERVED
> (for some reason). For us it does not matter whether the page is reserved or
> not, if it is kernel visible page then it is DDR.
> >
>
> I think you are setting I|G by addressing all mmio pages, right? If so,
>
> KVM: direct mmio pfn check
>
> Userspace may specify memory slots that are backed by mmio pages rather
> than
> normal RAM. In some cases it is not enough to identify these mmio pages
> by pfn_valid(). This patch adds checking the PageReserved as well.
Do you know what are those "some cases" and how checking PageReserved helps in
those cases?
-Bharat
>
> Tiejun
>
> > -Bharat
> >
> >>
> >> Tiejun
> >>
> >>> + mas2_attr |= MAS2_I | MAS2_G;
> >>> + } else {
> >>> #ifdef CONFIG_SMP
> >>> - return (mas2 & MAS2_ATTRIB_MASK) | MAS2_M;
> >>> -#else
> >>> - return mas2 & MAS2_ATTRIB_MASK;
> >>> + mas2_attr |= MAS2_M;
> >>> #endif
> >>> + }
> >>> + return mas2_attr;
> >>> }
> >>>
> >>> /*
> >>> @@ -313,7 +320,7 @@ static void kvmppc_e500_setup_stlbe(
> >>> /* Force IPROT=0 for all guest mappings. */
> >>> stlbe->mas1 = MAS1_TSIZE(tsize) | get_tlb_sts(gtlbe) |
> >>> MAS1_VALID;
> >>> stlbe->mas2 = (gvaddr & MAS2_EPN) |
> >>> - e500_shadow_mas2_attrib(gtlbe->mas2, pr);
> >>> + e500_shadow_mas2_attrib(gtlbe->mas2, pfn);
> >>> stlbe->mas7_3 = ((u64)pfn << PAGE_SHIFT) |
> >>> e500_shadow_mas3_attrib(gtlbe->mas7_3, pr);
> >>>
> >>>
> >>
> >
>
> --
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