> -----Original Message----- > From: Benjamin Herrenschmidt [mailto:benh@xxxxxxxxxxxxxxxxxxx] > Sent: Saturday, July 27, 2013 3:57 AM > To: Bhushan Bharat-R65777 > Cc: Alexander Graf; kvm-ppc@xxxxxxxxxxxxxxx; kvm@xxxxxxxxxxxxxxx; linuxppc- > dev@xxxxxxxxxxxxxxxx; Wood Scott-B07421 > Subject: Re: [PATCH 4/4] kvm: powerpc: set cache coherency only for RAM pages > > On Fri, 2013-07-26 at 15:03 +0000, Bhushan Bharat-R65777 wrote: > > Will not searching the Linux PTE is a overkill? > > That's the best approach. Also we are searching it already to resolve the page > fault. That does mean we search twice but on the other hand that also means it's > hot in the cache. Below is early git diff (not a proper cleanup patch), to be sure that this is what we want on PowerPC and take early feedback. Also I run some benchmark to understand the overhead if any. Using kvm_is_mmio_pfn(); what the current patch does: Real: 0m46.616s + 0m49.517s + 0m49.510s + 0m46.936s + 0m46.889s + 0m46.684s = Avg; 47.692s User: 0m31.636s + 0m31.816s + 0m31.456s + 0m31.752s + 0m32.028s + 0m31.848s = Avg; 31.756s Sys: 0m11.596s + 0m11.868s + 0m12.244s + 0m11.672s + 0m11.356s + 0m11.432s = Avg; 11.695s Using kernel page table search (below changes): Real: 0m46.431s + 0m50.269s + 0m46.724s + 0m46.645s + 0m46.670s + 0m50.259s = Avg; 47.833s User: 0m31.568s + 0m31.816s + 0m31.444s + 0m31.808s + 0m31.312s + 0m31.740s = Avg; 31.614s Sys: 0m11.516s + 0m12.060s + 0m11.872s + 0m11.476s + 0m12.000s + 0m12.152s = Avg; 11.846s ------------------ diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h index 3328353..d6d0dac 100644 --- a/arch/powerpc/include/asm/kvm_host.h +++ b/arch/powerpc/include/asm/kvm_host.h @@ -532,6 +532,7 @@ struct kvm_vcpu_arch { u32 epr; u32 crit_save; struct kvmppc_booke_debug_reg dbg_reg; + pgd_t *pgdir; #endif gpa_t paddr_accessed; gva_t vaddr_accessed; diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c index 17722d8..ebcccc2 100644 --- a/arch/powerpc/kvm/booke.c +++ b/arch/powerpc/kvm/booke.c @@ -697,7 +697,7 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) #endif kvmppc_fix_ee_before_entry(); - + vcpu->arch.pgdir = current->mm->pgd; ret = __kvmppc_vcpu_run(kvm_run, vcpu); /* No need for kvm_guest_exit. It's done in handle_exit. diff --git a/arch/powerpc/kvm/e500.h b/arch/powerpc/kvm/e500.h index 4fd9650..fc4b2f6 100644 --- a/arch/powerpc/kvm/e500.h +++ b/arch/powerpc/kvm/e500.h @@ -31,11 +31,13 @@ enum vcpu_ftr { #define E500_TLB_NUM 2 /* entry is mapped somewhere in host TLB */ -#define E500_TLB_VALID (1 << 0) +#define E500_TLB_VALID (1 << 31) /* TLB1 entry is mapped by host TLB1, tracked by bitmaps */ -#define E500_TLB_BITMAP (1 << 1) +#define E500_TLB_BITMAP (1 << 30) /* TLB1 entry is mapped by host TLB0 */ -#define E500_TLB_TLB0 (1 << 2) +#define E500_TLB_TLB0 (1 << 29) +/* Lower 5 bits have WIMGE value */ +#define E500_TLB_WIMGE_MASK (0x1f) struct tlbe_ref { pfn_t pfn; /* valid only for TLB0, except briefly */ diff --git a/arch/powerpc/kvm/e500_mmu_host.c b/arch/powerpc/kvm/e500_mmu_host.c index 5cbdc8f..a48c13f 100644 --- a/arch/powerpc/kvm/e500_mmu_host.c +++ b/arch/powerpc/kvm/e500_mmu_host.c @@ -40,6 +40,84 @@ static struct kvmppc_e500_tlb_params host_tlb_params[E500_TLB_NUM]; +/* + * find_linux_pte returns the address of a linux pte for a given + * effective address and directory. If not found, it returns zero. + */ +static inline pte_t *find_linux_pte(pgd_t *pgdir, unsigned long ea) +{ + pgd_t *pg; + pud_t *pu; + pmd_t *pm; + pte_t *pt = NULL; + + pg = pgdir + pgd_index(ea); + if (!pgd_none(*pg)) { + pu = pud_offset(pg, ea); + if (!pud_none(*pu)) { + pm = pmd_offset(pu, ea); + if (pmd_present(*pm)) + pt = pte_offset_kernel(pm, ea); + } + } + return pt; +} + +#ifdef CONFIG_HUGETLB_PAGE +pte_t *find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea, + unsigned *shift); +#else +static inline pte_t *find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea, + unsigned *shift) +{ + if (shift) + *shift = 0; + return find_linux_pte(pgdir, ea); +} +#endif /* !CONFIG_HUGETLB_PAGE */ + +/* + * Lock and read a linux PTE. If it's present and writable, atomically + * set dirty and referenced bits and return the PTE, otherwise return 0. + */ +static inline pte_t kvmppc_read_update_linux_pte(pte_t *p, int writing) +{ + pte_t pte = pte_val(*p); + + if (pte_present(pte)) { + pte = pte_mkyoung(pte); + if (writing && pte_write(pte)) + pte = pte_mkdirty(pte); + } + + *p = pte; + + return pte; +} + +static pte_t lookup_linux_pte(pgd_t *pgdir, unsigned long hva, + int writing, unsigned long *pte_sizep) +{ + pte_t *ptep; + unsigned long ps = *pte_sizep; + unsigned int shift; + + ptep = find_linux_pte_or_hugepte(pgdir, hva, &shift); + if (!ptep) + return __pte(0); + if (shift) + *pte_sizep = 1ul << shift; + else + *pte_sizep = PAGE_SIZE; + + if (ps > *pte_sizep) + return __pte(0); + if (!pte_present(*ptep)) + return __pte(0); + + return kvmppc_read_update_linux_pte(ptep, writing); +} + static inline unsigned int tlb1_max_shadow_size(void) { /* reserve one entry for magic page */ @@ -262,10 +340,11 @@ static inline int tlbe_is_writable(struct kvm_book3e_206_tlb_entry *tlbe) static inline void kvmppc_e500_ref_setup(struct tlbe_ref *ref, struct kvm_book3e_206_tlb_entry *gtlbe, - pfn_t pfn) + pfn_t pfn, int wimg) { ref->pfn = pfn; ref->flags |= E500_TLB_VALID; + ref->flags |= (gtlbe->mas2 & MAS2_ATTRIB_MASK) | wimg; if (tlbe_is_writable(gtlbe)) kvm_set_pfn_dirty(pfn); @@ -326,8 +405,8 @@ 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, pfn); + stlbe->mas2 = (gvaddr & MAS2_EPN) | (ref->flags & E500_TLB_WIMGE_MASK); +// e500_shadow_mas2_attrib(gtlbe->mas2, pfn); stlbe->mas7_3 = ((u64)pfn << PAGE_SHIFT) | e500_shadow_mas3_attrib(gtlbe->mas7_3, pr); @@ -346,6 +425,8 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500, unsigned long hva; int pfnmap = 0; int tsize = BOOK3E_PAGESZ_4K; + pte_t pte; + int wimg = 0; /* * Translate guest physical to true physical, acquiring @@ -451,6 +532,8 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500, if (likely(!pfnmap)) { unsigned long tsize_pages = 1 << (tsize + 10 - PAGE_SHIFT); + pgd_t *pgdir; + pfn = gfn_to_pfn_memslot(slot, gfn); if (is_error_noslot_pfn(pfn)) { printk(KERN_ERR "Couldn't get real page for gfn %lx!\n", @@ -461,9 +544,15 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500, /* Align guest and physical address to page map boundaries */ pfn &= ~(tsize_pages - 1); gvaddr &= ~((tsize_pages << PAGE_SHIFT) - 1); + pgdir = vcpu_e500->vcpu.arch.pgdir; + pte = lookup_linux_pte(pgdir, hva, 1, &tsize_pages); + if (pte_present(pte)) + wimg = (pte >> PTE_WIMGE_SHIFT) & MAS2_WIMGE_MASK; + else + wimg = MAS2_I | MAS2_G; } - kvmppc_e500_ref_setup(ref, gtlbe, pfn); + kvmppc_e500_ref_setup(ref, gtlbe, pfn, wimg); kvmppc_e500_setup_stlbe(&vcpu_e500->vcpu, gtlbe, tsize, ref, gvaddr, stlbe); --------------------------------------- > > Cheers, > Ben > > ��.n��������+%������w��{.n�����o�^n�r������&��z�ޗ�zf���h���~����������_��+v���)ߣ�
