From a1b4a0f6064aacad0d708105e6f60a06e93fbf37 Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Thu, 18 Apr 2013 19:50:24 +0000 Subject: [PATCH] KVM: PPC: Book3S HV: Make HPT reading code notice R/C bit changes At present, the code that determines whether a HPT entry has changed, and thus needs to be sent to userspace when it is copying the HPT, doesn't consider a hardware update to the reference and change bits (R and C) in the HPT entries to constitute a change that needs to be sent to userspace. This adds code to check for changes in R and C when we are scanning the HPT to find changed entries, and adds code to set the changed flag for the HPTE when we update the R and C bits in the guest view of the HPTE. Since we now need to set the HPTE changed flag in book3s_64_mmu_hv.c as well as book3s_hv_rm_mmu.c, we move the note_hpte_modification() function into kvm_book3s_64.h. Current Linux guest kernels don't use the hardware updates of R and C in the HPT, so this change won't affect them. Linux (or other) kernels might in future want to use the R and C bits and have them correctly transferred across when a guest is migrated, so it is better to correct this deficiency. Signed-off-by: Paul Mackerras Signed-off-by: Alexander Graf --- arch/powerpc/include/asm/kvm_book3s_64.h | 13 ++++++ arch/powerpc/kvm/book3s_64_mmu_hv.c | 59 ++++++++++++++++++++---- arch/powerpc/kvm/book3s_hv_rm_mmu.c | 11 ----- 3 files changed, 63 insertions(+), 20 deletions(-) diff --git a/arch/powerpc/include/asm/kvm_book3s_64.h b/arch/powerpc/include/asm/kvm_book3s_64.h index 38bec1dc9928..9c1ff330c805 100644 --- a/arch/powerpc/include/asm/kvm_book3s_64.h +++ b/arch/powerpc/include/asm/kvm_book3s_64.h @@ -268,4 +268,17 @@ static inline int is_vrma_hpte(unsigned long hpte_v) (HPTE_V_1TB_SEG | (VRMA_VSID << (40 - 16))); } +#ifdef CONFIG_KVM_BOOK3S_64_HV +/* + * Note modification of an HPTE; set the HPTE modified bit + * if anyone is interested. + */ +static inline void note_hpte_modification(struct kvm *kvm, + struct revmap_entry *rev) +{ + if (atomic_read(&kvm->arch.hpte_mod_interest)) + rev->guest_rpte |= HPTE_GR_MODIFIED; +} +#endif /* CONFIG_KVM_BOOK3S_64_HV */ + #endif /* __ASM_KVM_BOOK3S_64_H__ */ diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c index 8cc18abd6dde..d641a6634b02 100644 --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c @@ -893,7 +893,10 @@ static int kvm_unmap_rmapp(struct kvm *kvm, unsigned long *rmapp, /* Harvest R and C */ rcbits = hptep[1] & (HPTE_R_R | HPTE_R_C); *rmapp |= rcbits << KVMPPC_RMAP_RC_SHIFT; - rev[i].guest_rpte = ptel | rcbits; + if (rcbits & ~rev[i].guest_rpte) { + rev[i].guest_rpte = ptel | rcbits; + note_hpte_modification(kvm, &rev[i]); + } } unlock_rmap(rmapp); hptep[0] &= ~HPTE_V_HVLOCK; @@ -976,7 +979,10 @@ static int kvm_age_rmapp(struct kvm *kvm, unsigned long *rmapp, /* Now check and modify the HPTE */ if ((hptep[0] & HPTE_V_VALID) && (hptep[1] & HPTE_R_R)) { kvmppc_clear_ref_hpte(kvm, hptep, i); - rev[i].guest_rpte |= HPTE_R_R; + if (!(rev[i].guest_rpte & HPTE_R_R)) { + rev[i].guest_rpte |= HPTE_R_R; + note_hpte_modification(kvm, &rev[i]); + } ret = 1; } hptep[0] &= ~HPTE_V_HVLOCK; @@ -1080,7 +1086,10 @@ static int kvm_test_clear_dirty(struct kvm *kvm, unsigned long *rmapp) hptep[1] &= ~HPTE_R_C; eieio(); hptep[0] = (hptep[0] & ~HPTE_V_ABSENT) | HPTE_V_VALID; - rev[i].guest_rpte |= HPTE_R_C; + if (!(rev[i].guest_rpte & HPTE_R_C)) { + rev[i].guest_rpte |= HPTE_R_C; + note_hpte_modification(kvm, &rev[i]); + } ret = 1; } hptep[0] &= ~HPTE_V_HVLOCK; @@ -1193,16 +1202,36 @@ struct kvm_htab_ctx { #define HPTE_SIZE (2 * sizeof(unsigned long)) +/* + * Returns 1 if this HPT entry has been modified or has pending + * R/C bit changes. + */ +static int hpte_dirty(struct revmap_entry *revp, unsigned long *hptp) +{ + unsigned long rcbits_unset; + + if (revp->guest_rpte & HPTE_GR_MODIFIED) + return 1; + + /* Also need to consider changes in reference and changed bits */ + rcbits_unset = ~revp->guest_rpte & (HPTE_R_R | HPTE_R_C); + if ((hptp[0] & HPTE_V_VALID) && (hptp[1] & rcbits_unset)) + return 1; + + return 0; +} + static long record_hpte(unsigned long flags, unsigned long *hptp, unsigned long *hpte, struct revmap_entry *revp, int want_valid, int first_pass) { unsigned long v, r; + unsigned long rcbits_unset; int ok = 1; int valid, dirty; /* Unmodified entries are uninteresting except on the first pass */ - dirty = !!(revp->guest_rpte & HPTE_GR_MODIFIED); + dirty = hpte_dirty(revp, hptp); if (!first_pass && !dirty) return 0; @@ -1223,16 +1252,28 @@ static long record_hpte(unsigned long flags, unsigned long *hptp, while (!try_lock_hpte(hptp, HPTE_V_HVLOCK)) cpu_relax(); v = hptp[0]; + + /* re-evaluate valid and dirty from synchronized HPTE value */ + valid = !!(v & HPTE_V_VALID); + dirty = !!(revp->guest_rpte & HPTE_GR_MODIFIED); + + /* Harvest R and C into guest view if necessary */ + rcbits_unset = ~revp->guest_rpte & (HPTE_R_R | HPTE_R_C); + if (valid && (rcbits_unset & hptp[1])) { + revp->guest_rpte |= (hptp[1] & (HPTE_R_R | HPTE_R_C)) | + HPTE_GR_MODIFIED; + dirty = 1; + } + if (v & HPTE_V_ABSENT) { v &= ~HPTE_V_ABSENT; v |= HPTE_V_VALID; + valid = 1; } - /* re-evaluate valid and dirty from synchronized HPTE value */ - valid = !!(v & HPTE_V_VALID); if ((flags & KVM_GET_HTAB_BOLTED_ONLY) && !(v & HPTE_V_BOLTED)) valid = 0; - r = revp->guest_rpte | (hptp[1] & (HPTE_R_R | HPTE_R_C)); - dirty = !!(revp->guest_rpte & HPTE_GR_MODIFIED); + + r = revp->guest_rpte; /* only clear modified if this is the right sort of entry */ if (valid == want_valid && dirty) { r &= ~HPTE_GR_MODIFIED; @@ -1288,7 +1329,7 @@ static ssize_t kvm_htab_read(struct file *file, char __user *buf, /* Skip uninteresting entries, i.e. clean on not-first pass */ if (!first_pass) { while (i < kvm->arch.hpt_npte && - !(revp->guest_rpte & HPTE_GR_MODIFIED)) { + !hpte_dirty(revp, hptp)) { ++i; hptp += 2; ++revp; diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c index 19c93bae1aea..6dcbb49105a4 100644 --- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c +++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c @@ -97,17 +97,6 @@ void kvmppc_add_revmap_chain(struct kvm *kvm, struct revmap_entry *rev, } EXPORT_SYMBOL_GPL(kvmppc_add_revmap_chain); -/* - * Note modification of an HPTE; set the HPTE modified bit - * if anyone is interested. - */ -static inline void note_hpte_modification(struct kvm *kvm, - struct revmap_entry *rev) -{ - if (atomic_read(&kvm->arch.hpte_mod_interest)) - rev->guest_rpte |= HPTE_GR_MODIFIED; -} - /* Remove this HPTE from the chain for a real page */ static void remove_revmap_chain(struct kvm *kvm, long pte_index, struct revmap_entry *rev, -- 2.30.2