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KVM: MMU: Switch to mmu spinlock

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Convert the synchronization of the shadow handling to a separate mmu_lock
spinlock.

Also guard fetch() by mmap_sem in read-mode to protect against alias
and memslot changes.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
This commit is contained in:
Marcelo Tosatti 2007-12-20 19:18:26 -05:00 committed by Avi Kivity
parent d7824fff89
commit aaee2c94f7
5 changed files with 35 additions and 31 deletions
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48
arch/x86/kvm/mmu.c
View file

@ -971,16 +971,12 @@ static void nonpaging_new_cr3(struct kvm_vcpu *vcpu)
{
}
static int __nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, int write, gfn_t gfn)
static int __nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, int write,
gfn_t gfn, struct page *page)
{
int level = PT32E_ROOT_LEVEL;
hpa_t table_addr = vcpu->arch.mmu.root_hpa;
int pt_write = 0;
struct page *page;
down_read(&current->mm->mmap_sem);
page = gfn_to_page(vcpu->kvm, gfn);
up_read(&current->mm->mmap_sem);
for (; ; level--) {
u32 index = PT64_INDEX(v, level);
@ -1022,9 +1018,17 @@ static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, int write, gfn_t gfn)
{
int r;
mutex_lock(&vcpu->kvm->lock);
r = __nonpaging_map(vcpu, v, write, gfn);
mutex_unlock(&vcpu->kvm->lock);
struct page *page;
down_read(&current->mm->mmap_sem);
page = gfn_to_page(vcpu->kvm, gfn);
spin_lock(&vcpu->kvm->mmu_lock);
r = __nonpaging_map(vcpu, v, write, gfn, page);
spin_unlock(&vcpu->kvm->mmu_lock);
up_read(&current->mm->mmap_sem);
return r;
}
@ -1045,7 +1049,7 @@ static void mmu_free_roots(struct kvm_vcpu *vcpu)
if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
return;
mutex_lock(&vcpu->kvm->lock);
spin_lock(&vcpu->kvm->mmu_lock);
#ifdef CONFIG_X86_64
if (vcpu->arch.mmu.shadow_root_level == PT64_ROOT_LEVEL) {
hpa_t root = vcpu->arch.mmu.root_hpa;
@ -1053,7 +1057,7 @@ static void mmu_free_roots(struct kvm_vcpu *vcpu)
sp = page_header(root);
--sp->root_count;
vcpu->arch.mmu.root_hpa = INVALID_PAGE;
mutex_unlock(&vcpu->kvm->lock);
spin_unlock(&vcpu->kvm->mmu_lock);
return;
}
#endif
@ -1067,7 +1071,7 @@ static void mmu_free_roots(struct kvm_vcpu *vcpu)
}
vcpu->arch.mmu.pae_root[i] = INVALID_PAGE;
}
mutex_unlock(&vcpu->kvm->lock);
spin_unlock(&vcpu->kvm->mmu_lock);
vcpu->arch.mmu.root_hpa = INVALID_PAGE;
}
@ -1270,9 +1274,9 @@ int kvm_mmu_load(struct kvm_vcpu *vcpu)
r = mmu_topup_memory_caches(vcpu);
if (r)
goto out;
mutex_lock(&vcpu->kvm->lock);
spin_lock(&vcpu->kvm->mmu_lock);
mmu_alloc_roots(vcpu);
mutex_unlock(&vcpu->kvm->lock);
spin_unlock(&vcpu->kvm->mmu_lock);
kvm_x86_ops->set_cr3(vcpu, vcpu->arch.mmu.root_hpa);
kvm_mmu_flush_tlb(vcpu);
out:
@ -1408,7 +1412,7 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
pgprintk("%s: gpa %llx bytes %d\n", __FUNCTION__, gpa, bytes);
mmu_guess_page_from_pte_write(vcpu, gpa, new, bytes);
mutex_lock(&vcpu->kvm->lock);
spin_lock(&vcpu->kvm->mmu_lock);
++vcpu->kvm->stat.mmu_pte_write;
kvm_mmu_audit(vcpu, "pre pte write");
if (gfn == vcpu->arch.last_pt_write_gfn
@ -1477,7 +1481,7 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
}
}
kvm_mmu_audit(vcpu, "post pte write");
mutex_unlock(&vcpu->kvm->lock);
spin_unlock(&vcpu->kvm->mmu_lock);
if (vcpu->arch.update_pte.page) {
kvm_release_page_clean(vcpu->arch.update_pte.page);
vcpu->arch.update_pte.page = NULL;
@ -1493,15 +1497,15 @@ int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva)
gpa = vcpu->arch.mmu.gva_to_gpa(vcpu, gva);
up_read(&current->mm->mmap_sem);
mutex_lock(&vcpu->kvm->lock);
spin_lock(&vcpu->kvm->mmu_lock);
r = kvm_mmu_unprotect_page(vcpu->kvm, gpa >> PAGE_SHIFT);
mutex_unlock(&vcpu->kvm->lock);
spin_unlock(&vcpu->kvm->mmu_lock);
return r;
}
void __kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu)
{
mutex_lock(&vcpu->kvm->lock);
spin_lock(&vcpu->kvm->mmu_lock);
while (vcpu->kvm->arch.n_free_mmu_pages < KVM_REFILL_PAGES) {
struct kvm_mmu_page *sp;
@ -1510,7 +1514,7 @@ void __kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu)
kvm_mmu_zap_page(vcpu->kvm, sp);
++vcpu->kvm->stat.mmu_recycled;
}
mutex_unlock(&vcpu->kvm->lock);
spin_unlock(&vcpu->kvm->mmu_lock);
}
int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u32 error_code)
@ -1642,10 +1646,10 @@ void kvm_mmu_zap_all(struct kvm *kvm)
{
struct kvm_mmu_page *sp, *node;
mutex_lock(&kvm->lock);
spin_lock(&kvm->mmu_lock);
list_for_each_entry_safe(sp, node, &kvm->arch.active_mmu_pages, link)
kvm_mmu_zap_page(kvm, sp);
mutex_unlock(&kvm->lock);
spin_unlock(&kvm->mmu_lock);
kvm_flush_remote_tlbs(kvm);
}

10
arch/x86/kvm/paging_tmpl.h
View file

@ -387,7 +387,6 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
*/
r = FNAME(walk_addr)(&walker, vcpu, addr, write_fault, user_fault,
fetch_fault);
up_read(&current->mm->mmap_sem);
/*
* The page is not mapped by the guest. Let the guest handle it.
@ -396,12 +395,13 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
pgprintk("%s: guest page fault\n", __FUNCTION__);
inject_page_fault(vcpu, addr, walker.error_code);
vcpu->arch.last_pt_write_count = 0; /* reset fork detector */
up_read(&current->mm->mmap_sem);
return 0;
}
page = gfn_to_page(vcpu->kvm, walker.gfn);
mutex_lock(&vcpu->kvm->lock);
spin_lock(&vcpu->kvm->mmu_lock);
shadow_pte = FNAME(fetch)(vcpu, addr, &walker, user_fault, write_fault,
&write_pt, page);
pgprintk("%s: shadow pte %p %llx ptwrite %d\n", __FUNCTION__,
@ -414,13 +414,15 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
* mmio: emulate if accessible, otherwise its a guest fault.
*/
if (shadow_pte && is_io_pte(*shadow_pte)) {
mutex_unlock(&vcpu->kvm->lock);
spin_unlock(&vcpu->kvm->mmu_lock);
up_read(&current->mm->mmap_sem);
return 1;
}
++vcpu->stat.pf_fixed;
kvm_mmu_audit(vcpu, "post page fault (fixed)");
mutex_unlock(&vcpu->kvm->lock);
spin_unlock(&vcpu->kvm->mmu_lock);
up_read(&current->mm->mmap_sem);
return write_pt;
}

2
arch/x86/kvm/vmx.c
View file

@ -1477,7 +1477,6 @@ static int alloc_apic_access_page(struct kvm *kvm)
struct kvm_userspace_memory_region kvm_userspace_mem;
int r = 0;
mutex_lock(&kvm->lock);
down_write(&current->mm->mmap_sem);
if (kvm->arch.apic_access_page)
goto out;
@ -1491,7 +1490,6 @@ static int alloc_apic_access_page(struct kvm *kvm)
kvm->arch.apic_access_page = gfn_to_page(kvm, 0xfee00);
out:
up_write(&current->mm->mmap_sem);
mutex_unlock(&kvm->lock);
return r;
}

3
include/linux/kvm_host.h
View file

@ -104,7 +104,8 @@ struct kvm_memory_slot {
};
struct kvm {
struct mutex lock; /* protects everything except vcpus */
struct mutex lock; /* protects the vcpus array and APIC accesses */
spinlock_t mmu_lock;
struct mm_struct *mm; /* userspace tied to this vm */
int nmemslots;
struct kvm_memory_slot memslots[KVM_MEMORY_SLOTS +

3
virt/kvm/kvm_main.c
View file

@ -165,6 +165,7 @@ static struct kvm *kvm_create_vm(void)
kvm->mm = current->mm;
atomic_inc(&kvm->mm->mm_count);
spin_lock_init(&kvm->mmu_lock);
kvm_io_bus_init(&kvm->pio_bus);
mutex_init(&kvm->lock);
kvm_io_bus_init(&kvm->mmio_bus);
@ -552,9 +553,7 @@ int kvm_read_guest_atomic(struct kvm *kvm, gpa_t gpa, void *data,
addr = gfn_to_hva(kvm, gfn);
if (kvm_is_error_hva(addr))
return -EFAULT;
pagefault_disable();
r = __copy_from_user_inatomic(data, (void __user *)addr + offset, len);
pagefault_enable();
if (r)
return -EFAULT;
return 0;