> -----Original Message----- > From: kvm-ppc-owner@xxxxxxxxxxxxxxx [mailto:kvm-ppc-owner@xxxxxxxxxxxxxxx] On > Behalf Of Alexander Graf > Sent: Thursday, July 18, 2013 8:23 PM > To: Bhushan Bharat-R65777 > Cc: kvm-ppc@xxxxxxxxxxxxxxx; kvm@xxxxxxxxxxxxxxx; Wood Scott-B07421; Bhushan > Bharat-R65777 > Subject: Re: [PATCH 2/2 v2] kvm: powerpc: set cache coherency only for kernel > managed pages > > > On 18.07.2013, at 15:19, Bharat Bhushan wrote: > > > If there is a struct page for the requested mapping then it's normal > > RAM and the mapping is set to "M" bit (coherent, cacheable) otherwise > > 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 <bharat.bhushan@xxxxxxxxxxxxx> > > --- > > v2: some cleanup and added comment > > - > > arch/powerpc/kvm/e500_mmu_host.c | 23 ++++++++++++++++++----- > > 1 files changed, 18 insertions(+), 5 deletions(-) > > > > diff --git a/arch/powerpc/kvm/e500_mmu_host.c > > b/arch/powerpc/kvm/e500_mmu_host.c > > index 1c6a9d7..02eb973 100644 > > --- a/arch/powerpc/kvm/e500_mmu_host.c > > +++ b/arch/powerpc/kvm/e500_mmu_host.c > > @@ -64,13 +64,26 @@ 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; > > + > > + /* > > + * RAM is always mappable on e500 systems, so this is identical > > + * to kvm_is_mmio_pfn(), just without its overhead. > > + */ > > + if (!pfn_valid(pfn)) { > > + /* Pages not managed by Kernel are treated as I/O, set I + G */ > > Please also document the intermediate thought that I/O should be mapped non- > cached. I did not get what you mean to document? > > > + mas2_attr |= MAS2_I | MAS2_G; > > #ifdef CONFIG_SMP > > Please separate the SMP case out of the branch. Really :) this was looking simple to me. > > > - return (mas2 & MAS2_ATTRIB_MASK) | MAS2_M; > > -#else > > - return mas2 & MAS2_ATTRIB_MASK; > > + } else { > > + /* Kernel managed pages are actually RAM so set "M" */ > > This comment doesn't tell me why M can be set ;). RAM in SMP, so setting coherent, is not that obvious? -Bharat > > > Alex > > > + mas2_attr |= MAS2_M; > > #endif > > + } > > + return mas2_attr; > > } > > > > /* > > @@ -313,7 +326,7 @@ 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); > > > > -- > > 1.7.0.4 > > > > > > -- > > To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in > > the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info > > at http://vger.kernel.org/majordomo-info.html > > -- > To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body > of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at > http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
