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[PATCH v2 2/2] MIPS: KVM: remove shadow_tlb code

To: John Crispin <blogic@openwrt.org>, Ralf Baechle <ralf@linux-mips.org>, <linux-mips@linux-mips.org>
Subject: [PATCH v2 2/2] MIPS: KVM: remove shadow_tlb code
From: James Hogan <james.hogan@imgtec.com>
Date: Fri, 17 Jan 2014 12:01:31 +0000
Cc: James Hogan <james.hogan@imgtec.com>, Gleb Natapov <gleb@redhat.com>, <kvm@vger.kernel.org>, Sanjay Lal <sanjayl@kymasys.com>
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The kvm_mips_init_shadow_tlb() function is called from
kvm_arch_vcpu_init() and initialises entries 0 to
current_cpu_data.tlbsize-1 of the virtual cpu's shadow_tlb[64] array.

However newer cores with FTLBs can have a tlbsize > 64, for example the
ProAptiv I'm testing on has a total tlbsize of 576. This causes
kvm_mips_init_shadow_tlb() to overflow the shadow_tlb[64] array and
overwrite the comparecount_timer among other things, causing a lock up
when starting a KVM guest.

Aside from kvm_mips_init_shadow_tlb() which only initialises it, the
shadow_tlb[64] array is only actually used by the following functions:
 - kvm_shadow_tlb_put() & kvm_shadow_tlb_load()
     These are never called. The only call sites are #if 0'd out.
 - kvm_mips_dump_shadow_tlbs()
     This is never called.

It was originally added for trap & emulate, but turned out to be
unnecessary so it was disabled.

So instead of fixing the shadow_tlb initialisation code, lets just
remove the shadow_tlb[64] array and the above functions entirely. The
only functional change here is the removal of broken shadow_tlb
initialisation. The rest just deletes dead code.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: John Crispin <blogic@openwrt.org>
Cc: linux-mips@linux-mips.org
Cc: Gleb Natapov <gleb@redhat.com>
Cc: kvm@vger.kernel.org
Cc: Sanjay Lal <sanjayl@kymasys.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
---
This is based on John Crispin's mips-next-3.14 branch where FTLB support
is applied.

v2:
- Rewrite commit message to be a bit clearer and more explicit (on John
  Crispin's suggestion).
---
 arch/mips/include/asm/kvm_host.h |   7 ---
 arch/mips/kvm/kvm_mips.c         |   1 -
 arch/mips/kvm/kvm_tlb.c          | 130 ---------------------------------------
 3 files changed, 138 deletions(-)

diff --git a/arch/mips/include/asm/kvm_host.h b/arch/mips/include/asm/kvm_host.h
index 32966969f2f9..a995fce87791 100644
--- a/arch/mips/include/asm/kvm_host.h
+++ b/arch/mips/include/asm/kvm_host.h
@@ -391,9 +391,6 @@ struct kvm_vcpu_arch {
        uint32_t guest_kernel_asid[NR_CPUS];
        struct mm_struct guest_kernel_mm, guest_user_mm;
 
-       struct kvm_mips_tlb shadow_tlb[NR_CPUS][KVM_MIPS_GUEST_TLB_SIZE];
-
-
        struct hrtimer comparecount_timer;
 
        int last_sched_cpu;
@@ -529,7 +526,6 @@ extern enum emulation_result 
kvm_mips_handle_tlbmod(unsigned long cause,
 
 extern void kvm_mips_dump_host_tlbs(void);
 extern void kvm_mips_dump_guest_tlbs(struct kvm_vcpu *vcpu);
-extern void kvm_mips_dump_shadow_tlbs(struct kvm_vcpu *vcpu);
 extern void kvm_mips_flush_host_tlb(int skip_kseg0);
 extern int kvm_mips_host_tlb_inv(struct kvm_vcpu *vcpu, unsigned long entryhi);
 extern int kvm_mips_host_tlb_inv_index(struct kvm_vcpu *vcpu, int index);
@@ -541,10 +537,7 @@ extern unsigned long 
kvm_mips_translate_guest_kseg0_to_hpa(struct kvm_vcpu *vcpu
                                                   unsigned long gva);
 extern void kvm_get_new_mmu_context(struct mm_struct *mm, unsigned long cpu,
                                    struct kvm_vcpu *vcpu);
-extern void kvm_shadow_tlb_put(struct kvm_vcpu *vcpu);
-extern void kvm_shadow_tlb_load(struct kvm_vcpu *vcpu);
 extern void kvm_local_flush_tlb_all(void);
-extern void kvm_mips_init_shadow_tlb(struct kvm_vcpu *vcpu);
 extern void kvm_mips_alloc_new_mmu_context(struct kvm_vcpu *vcpu);
 extern void kvm_mips_vcpu_load(struct kvm_vcpu *vcpu, int cpu);
 extern void kvm_mips_vcpu_put(struct kvm_vcpu *vcpu);
diff --git a/arch/mips/kvm/kvm_mips.c b/arch/mips/kvm/kvm_mips.c
index 73b34827826c..da5186fbd77a 100644
--- a/arch/mips/kvm/kvm_mips.c
+++ b/arch/mips/kvm/kvm_mips.c
@@ -1001,7 +1001,6 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
        hrtimer_init(&vcpu->arch.comparecount_timer, CLOCK_MONOTONIC,
                     HRTIMER_MODE_REL);
        vcpu->arch.comparecount_timer.function = kvm_mips_comparecount_wakeup;
-       kvm_mips_init_shadow_tlb(vcpu);
        return 0;
 }
 
diff --git a/arch/mips/kvm/kvm_tlb.c b/arch/mips/kvm/kvm_tlb.c
index 52083ea7fddd..68e6563915cd 100644
--- a/arch/mips/kvm/kvm_tlb.c
+++ b/arch/mips/kvm/kvm_tlb.c
@@ -145,30 +145,6 @@ void kvm_mips_dump_guest_tlbs(struct kvm_vcpu *vcpu)
        }
 }
 
-void kvm_mips_dump_shadow_tlbs(struct kvm_vcpu *vcpu)
-{
-       int i;
-       volatile struct kvm_mips_tlb tlb;
-
-       printk("Shadow TLBs:\n");
-       for (i = 0; i < KVM_MIPS_GUEST_TLB_SIZE; i++) {
-               tlb = vcpu->arch.shadow_tlb[smp_processor_id()][i];
-               printk("TLB%c%3d Hi 0x%08lx ",
-                      (tlb.tlb_lo0 | tlb.tlb_lo1) & MIPS3_PG_V ? ' ' : '*',
-                      i, tlb.tlb_hi);
-               printk("Lo0=0x%09" PRIx64 " %c%c attr %lx ",
-                      (uint64_t) mips3_tlbpfn_to_paddr(tlb.tlb_lo0),
-                      (tlb.tlb_lo0 & MIPS3_PG_D) ? 'D' : ' ',
-                      (tlb.tlb_lo0 & MIPS3_PG_G) ? 'G' : ' ',
-                      (tlb.tlb_lo0 >> 3) & 7);
-               printk("Lo1=0x%09" PRIx64 " %c%c attr %lx sz=%lx\n",
-                      (uint64_t) mips3_tlbpfn_to_paddr(tlb.tlb_lo1),
-                      (tlb.tlb_lo1 & MIPS3_PG_D) ? 'D' : ' ',
-                      (tlb.tlb_lo1 & MIPS3_PG_G) ? 'G' : ' ',
-                      (tlb.tlb_lo1 >> 3) & 7, tlb.tlb_mask);
-       }
-}
-
 static int kvm_mips_map_page(struct kvm *kvm, gfn_t gfn)
 {
        int srcu_idx, err = 0;
@@ -655,70 +631,6 @@ kvm_get_new_mmu_context(struct mm_struct *mm, unsigned 
long cpu,
        cpu_context(cpu, mm) = asid_cache(cpu) = asid;
 }
 
-void kvm_shadow_tlb_put(struct kvm_vcpu *vcpu)
-{
-       unsigned long flags;
-       unsigned long old_entryhi;
-       unsigned long old_pagemask;
-       int entry = 0;
-       int cpu = smp_processor_id();
-
-       local_irq_save(flags);
-
-       old_entryhi = read_c0_entryhi();
-       old_pagemask = read_c0_pagemask();
-
-       for (entry = 0; entry < current_cpu_data.tlbsize; entry++) {
-               write_c0_index(entry);
-               mtc0_tlbw_hazard();
-               tlb_read();
-               tlbw_use_hazard();
-
-               vcpu->arch.shadow_tlb[cpu][entry].tlb_hi = read_c0_entryhi();
-               vcpu->arch.shadow_tlb[cpu][entry].tlb_lo0 = read_c0_entrylo0();
-               vcpu->arch.shadow_tlb[cpu][entry].tlb_lo1 = read_c0_entrylo1();
-               vcpu->arch.shadow_tlb[cpu][entry].tlb_mask = read_c0_pagemask();
-       }
-
-       write_c0_entryhi(old_entryhi);
-       write_c0_pagemask(old_pagemask);
-       mtc0_tlbw_hazard();
-
-       local_irq_restore(flags);
-
-}
-
-void kvm_shadow_tlb_load(struct kvm_vcpu *vcpu)
-{
-       unsigned long flags;
-       unsigned long old_ctx;
-       int entry;
-       int cpu = smp_processor_id();
-
-       local_irq_save(flags);
-
-       old_ctx = read_c0_entryhi();
-
-       for (entry = 0; entry < current_cpu_data.tlbsize; entry++) {
-               write_c0_entryhi(vcpu->arch.shadow_tlb[cpu][entry].tlb_hi);
-               mtc0_tlbw_hazard();
-               write_c0_entrylo0(vcpu->arch.shadow_tlb[cpu][entry].tlb_lo0);
-               write_c0_entrylo1(vcpu->arch.shadow_tlb[cpu][entry].tlb_lo1);
-
-               write_c0_index(entry);
-               mtc0_tlbw_hazard();
-
-               tlb_write_indexed();
-               tlbw_use_hazard();
-       }
-
-       tlbw_use_hazard();
-       write_c0_entryhi(old_ctx);
-       mtc0_tlbw_hazard();
-       local_irq_restore(flags);
-}
-
-
 void kvm_local_flush_tlb_all(void)
 {
        unsigned long flags;
@@ -747,30 +659,6 @@ void kvm_local_flush_tlb_all(void)
        local_irq_restore(flags);
 }
 
-void kvm_mips_init_shadow_tlb(struct kvm_vcpu *vcpu)
-{
-       int cpu, entry;
-
-       for_each_possible_cpu(cpu) {
-               for (entry = 0; entry < current_cpu_data.tlbsize; entry++) {
-                       vcpu->arch.shadow_tlb[cpu][entry].tlb_hi =
-                           UNIQUE_ENTRYHI(entry);
-                       vcpu->arch.shadow_tlb[cpu][entry].tlb_lo0 = 0x0;
-                       vcpu->arch.shadow_tlb[cpu][entry].tlb_lo1 = 0x0;
-                       vcpu->arch.shadow_tlb[cpu][entry].tlb_mask =
-                           read_c0_pagemask();
-#ifdef DEBUG
-                       kvm_debug
-                           ("shadow_tlb[%d][%d]: tlb_hi: %#lx, lo0: %#lx, lo1: 
%#lx\n",
-                            cpu, entry,
-                            vcpu->arch.shadow_tlb[cpu][entry].tlb_hi,
-                            vcpu->arch.shadow_tlb[cpu][entry].tlb_lo0,
-                            vcpu->arch.shadow_tlb[cpu][entry].tlb_lo1);
-#endif
-               }
-       }
-}
-
 /* Restore ASID once we are scheduled back after preemption */
 void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 {
@@ -808,14 +696,6 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
                         vcpu->arch.last_sched_cpu, cpu, vcpu->vcpu_id);
        }
 
-       /* Only reload shadow host TLB if new ASIDs haven't been allocated */
-#if 0
-       if ((atomic_read(&kvm_mips_instance) > 1) && !newasid) {
-               kvm_mips_flush_host_tlb(0);
-               kvm_shadow_tlb_load(vcpu);
-       }
-#endif
-
        if (!newasid) {
                /* If we preempted while the guest was executing, then reload 
the pre-empted ASID */
                if (current->flags & PF_VCPU) {
@@ -861,12 +741,6 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
        vcpu->arch.preempt_entryhi = read_c0_entryhi();
        vcpu->arch.last_sched_cpu = cpu;
 
-#if 0
-       if ((atomic_read(&kvm_mips_instance) > 1)) {
-               kvm_shadow_tlb_put(vcpu);
-       }
-#endif
-
        if (((cpu_context(cpu, current->mm) ^ asid_cache(cpu)) &
             ASID_VERSION_MASK)) {
                kvm_debug("%s: Dropping MMU Context:  %#lx\n", __func__,
@@ -928,10 +802,8 @@ uint32_t kvm_get_inst(uint32_t *opc, struct kvm_vcpu *vcpu)
 }
 
 EXPORT_SYMBOL(kvm_local_flush_tlb_all);
-EXPORT_SYMBOL(kvm_shadow_tlb_put);
 EXPORT_SYMBOL(kvm_mips_handle_mapped_seg_tlb_fault);
 EXPORT_SYMBOL(kvm_mips_handle_commpage_tlb_fault);
-EXPORT_SYMBOL(kvm_mips_init_shadow_tlb);
 EXPORT_SYMBOL(kvm_mips_dump_host_tlbs);
 EXPORT_SYMBOL(kvm_mips_handle_kseg0_tlb_fault);
 EXPORT_SYMBOL(kvm_mips_host_tlb_lookup);
@@ -939,8 +811,6 @@ EXPORT_SYMBOL(kvm_mips_flush_host_tlb);
 EXPORT_SYMBOL(kvm_mips_guest_tlb_lookup);
 EXPORT_SYMBOL(kvm_mips_host_tlb_inv);
 EXPORT_SYMBOL(kvm_mips_translate_guest_kseg0_to_hpa);
-EXPORT_SYMBOL(kvm_shadow_tlb_load);
-EXPORT_SYMBOL(kvm_mips_dump_shadow_tlbs);
 EXPORT_SYMBOL(kvm_mips_dump_guest_tlbs);
 EXPORT_SYMBOL(kvm_get_inst);
 EXPORT_SYMBOL(kvm_arch_vcpu_load);
-- 
1.8.1.2



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