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Subject[PATCH 35/40] KVM: switch vcpu context to use SRCU
Date
From: Marcelo Tosatti <mtosatti@redhat.com>

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
---
arch/ia64/kvm/kvm-ia64.c | 15 ++++++---------
arch/s390/kvm/kvm-s390.h | 10 +++++++---
arch/x86/kvm/mmu.c | 7 +++----
arch/x86/kvm/vmx.c | 6 +++---
arch/x86/kvm/x86.c | 43 ++++++++++++++++++++++++-------------------
include/linux/kvm_host.h | 2 ++
6 files changed, 45 insertions(+), 38 deletions(-)
diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
index d0ad538..d5e3846 100644
--- a/arch/ia64/kvm/kvm-ia64.c
+++ b/arch/ia64/kvm/kvm-ia64.c
@@ -636,12 +636,9 @@ static void kvm_vcpu_post_transition(struct kvm_vcpu *vcpu)
static int __vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
{
union context *host_ctx, *guest_ctx;
- int r;
+ int r, idx;

- /*
- * down_read() may sleep and return with interrupts enabled
- */
- down_read(&vcpu->kvm->slots_lock);
+ idx = srcu_read_lock(&vcpu->kvm->srcu);

again:
if (signal_pending(current)) {
@@ -663,7 +660,7 @@ again:
if (r < 0)
goto vcpu_run_fail;

- up_read(&vcpu->kvm->slots_lock);
+ srcu_read_unlock(&vcpu->kvm->srcu, idx);
kvm_guest_enter();

/*
@@ -687,7 +684,7 @@ again:
kvm_guest_exit();
preempt_enable();

- down_read(&vcpu->kvm->slots_lock);
+ idx = srcu_read_lock(&vcpu->kvm->srcu);

r = kvm_handle_exit(kvm_run, vcpu);

@@ -697,10 +694,10 @@ again:
}

out:
- up_read(&vcpu->kvm->slots_lock);
+ srcu_read_unlock(&vcpu->kvm->srcu, idx);
if (r > 0) {
kvm_resched(vcpu);
- down_read(&vcpu->kvm->slots_lock);
+ idx = srcu_read_lock(&vcpu->kvm->srcu);
goto again;
}

diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
index 06cce82..60f09ab 100644
--- a/arch/s390/kvm/kvm-s390.h
+++ b/arch/s390/kvm/kvm-s390.h
@@ -67,10 +67,14 @@ static inline long kvm_s390_vcpu_get_memsize(struct kvm_vcpu *vcpu)

static inline void kvm_s390_vcpu_set_mem(struct kvm_vcpu *vcpu)
{
+ int idx;
struct kvm_memory_slot *mem;
+ struct kvm_memslots *memslots;

- down_read(&vcpu->kvm->slots_lock);
- mem = &vcpu->kvm->memslots[0];
+ idx = srcu_read_lock(&vcpu->kvm->srcu);
+ memslots = rcu_dereference(vcpu->kvm->memslots);
+
+ mem = &memslots->memslots[0];

vcpu->arch.sie_block->gmsor = mem->userspace_addr;
vcpu->arch.sie_block->gmslm =
@@ -78,7 +82,7 @@ static inline void kvm_s390_vcpu_set_mem(struct kvm_vcpu *vcpu)
(mem->npages << PAGE_SHIFT) +
VIRTIODESCSPACE - 1ul;

- up_read(&vcpu->kvm->slots_lock);
+ srcu_read_unlock(&vcpu->kvm->srcu, idx);
}

/* implemented in priv.c */
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index f8bf42a..25aabd0 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2933,10 +2933,9 @@ static int mmu_shrink(int nr_to_scan, gfp_t gfp_mask)
spin_lock(&kvm_lock);

list_for_each_entry(kvm, &vm_list, vm_list) {
- int npages;
+ int npages, idx;

- if (!down_read_trylock(&kvm->slots_lock))
- continue;
+ idx = srcu_read_lock(&kvm->srcu);
spin_lock(&kvm->mmu_lock);
npages = kvm->arch.n_alloc_mmu_pages -
kvm->arch.n_free_mmu_pages;
@@ -2949,7 +2948,7 @@ static int mmu_shrink(int nr_to_scan, gfp_t gfp_mask)
nr_to_scan--;

spin_unlock(&kvm->mmu_lock);
- up_read(&kvm->slots_lock);
+ srcu_read_unlock(&kvm->srcu, idx);
}
if (kvm_freed)
list_move_tail(&kvm_freed->vm_list, &vm_list);
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index f1cae7d..22ab713 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2478,10 +2478,10 @@ static int vmx_vcpu_reset(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
u64 msr;
- int ret;
+ int ret, idx;

vcpu->arch.regs_avail = ~((1 << VCPU_REGS_RIP) | (1 << VCPU_REGS_RSP));
- down_read(&vcpu->kvm->slots_lock);
+ idx = srcu_read_lock(&vcpu->kvm->srcu);
if (!init_rmode(vmx->vcpu.kvm)) {
ret = -ENOMEM;
goto out;
@@ -2589,7 +2589,7 @@ static int vmx_vcpu_reset(struct kvm_vcpu *vcpu)
vmx->emulation_required = 0;

out:
- up_read(&vcpu->kvm->slots_lock);
+ srcu_read_unlock(&vcpu->kvm->srcu, idx);
return ret;
}

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b9adeae..0cb795c 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1307,15 +1307,15 @@ static int __msr_io(struct kvm_vcpu *vcpu, struct kvm_msrs *msrs,
int (*do_msr)(struct kvm_vcpu *vcpu,
unsigned index, u64 *data))
{
- int i;
+ int i, idx;

vcpu_load(vcpu);

- down_read(&vcpu->kvm->slots_lock);
+ idx = srcu_read_lock(&vcpu->kvm->srcu);
for (i = 0; i < msrs->nmsrs; ++i)
if (do_msr(vcpu, entries[i].index, &entries[i].data))
break;
- up_read(&vcpu->kvm->slots_lock);
+ srcu_read_unlock(&vcpu->kvm->srcu, idx);

vcpu_put(vcpu);

@@ -3901,14 +3901,15 @@ static void vapic_enter(struct kvm_vcpu *vcpu)
static void vapic_exit(struct kvm_vcpu *vcpu)
{
struct kvm_lapic *apic = vcpu->arch.apic;
+ int idx;

if (!apic || !apic->vapic_addr)
return;

- down_read(&vcpu->kvm->slots_lock);
+ idx = srcu_read_lock(&vcpu->kvm->srcu);
kvm_release_page_dirty(apic->vapic_page);
mark_page_dirty(vcpu->kvm, apic->vapic_addr >> PAGE_SHIFT);
- up_read(&vcpu->kvm->slots_lock);
+ srcu_read_unlock(&vcpu->kvm->srcu, idx);
}

static void update_cr8_intercept(struct kvm_vcpu *vcpu)
@@ -4037,7 +4038,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
kvm_lapic_sync_to_vapic(vcpu);
}

- up_read(&vcpu->kvm->slots_lock);
+ srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);

kvm_guest_enter();

@@ -4079,7 +4080,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)

preempt_enable();

- down_read(&vcpu->kvm->slots_lock);
+ vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);

/*
* Profile KVM exit RIPs:
@@ -4101,6 +4102,7 @@ out:
static int __vcpu_run(struct kvm_vcpu *vcpu)
{
int r;
+ struct kvm *kvm = vcpu->kvm;

if (unlikely(vcpu->arch.mp_state == KVM_MP_STATE_SIPI_RECEIVED)) {
pr_debug("vcpu %d received sipi with vector # %x\n",
@@ -4112,7 +4114,7 @@ static int __vcpu_run(struct kvm_vcpu *vcpu)
vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
}

- down_read(&vcpu->kvm->slots_lock);
+ vcpu->srcu_idx = srcu_read_lock(&kvm->srcu);
vapic_enter(vcpu);

r = 1;
@@ -4120,9 +4122,9 @@ static int __vcpu_run(struct kvm_vcpu *vcpu)
if (vcpu->arch.mp_state == KVM_MP_STATE_RUNNABLE)
r = vcpu_enter_guest(vcpu);
else {
- up_read(&vcpu->kvm->slots_lock);
+ srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx);
kvm_vcpu_block(vcpu);
- down_read(&vcpu->kvm->slots_lock);
+ vcpu->srcu_idx = srcu_read_lock(&kvm->srcu);
if (test_and_clear_bit(KVM_REQ_UNHALT, &vcpu->requests))
{
switch(vcpu->arch.mp_state) {
@@ -4157,13 +4159,13 @@ static int __vcpu_run(struct kvm_vcpu *vcpu)
++vcpu->stat.signal_exits;
}
if (need_resched()) {
- up_read(&vcpu->kvm->slots_lock);
+ srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx);
kvm_resched(vcpu);
- down_read(&vcpu->kvm->slots_lock);
+ vcpu->srcu_idx = srcu_read_lock(&kvm->srcu);
}
}

- up_read(&vcpu->kvm->slots_lock);
+ srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx);
post_kvm_run_save(vcpu);

vapic_exit(vcpu);
@@ -4202,10 +4204,10 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
vcpu->mmio_read_completed = 1;
vcpu->mmio_needed = 0;

- down_read(&vcpu->kvm->slots_lock);
+ vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
r = emulate_instruction(vcpu, vcpu->arch.mmio_fault_cr2, 0,
EMULTYPE_NO_DECODE);
- up_read(&vcpu->kvm->slots_lock);
+ srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
if (r == EMULATE_DO_MMIO) {
/*
* Read-modify-write. Back to userspace.
@@ -4968,11 +4970,12 @@ int kvm_arch_vcpu_ioctl_translate(struct kvm_vcpu *vcpu,
{
unsigned long vaddr = tr->linear_address;
gpa_t gpa;
+ int idx;

vcpu_load(vcpu);
- down_read(&vcpu->kvm->slots_lock);
+ idx = srcu_read_lock(&vcpu->kvm->srcu);
gpa = vcpu->arch.mmu.gva_to_gpa(vcpu, vaddr);
- up_read(&vcpu->kvm->slots_lock);
+ srcu_read_unlock(&vcpu->kvm->srcu, idx);
tr->physical_address = gpa;
tr->valid = gpa != UNMAPPED_GVA;
tr->writeable = 1;
@@ -5224,11 +5227,13 @@ fail:

void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu)
{
+ int idx;
+
kfree(vcpu->arch.mce_banks);
kvm_free_lapic(vcpu);
- down_read(&vcpu->kvm->slots_lock);
+ idx = srcu_read_lock(&vcpu->kvm->srcu);
kvm_mmu_destroy(vcpu);
- up_read(&vcpu->kvm->slots_lock);
+ srcu_read_unlock(&vcpu->kvm->srcu, idx);
free_page((unsigned long)vcpu->arch.pio_data);
}

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 5e9cb90..0bb9aa2 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -83,6 +83,8 @@ struct kvm_vcpu {
struct kvm_run *run;
unsigned long requests;
unsigned long guest_debug;
+ int srcu_idx;
+
int fpu_active;
int guest_fpu_loaded;
wait_queue_head_t wq;
--
1.6.5.3


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