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KVM: remove the usage of the mmap_sem for the protection of the memory slots.

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This patch replaces the mmap_sem lock for the memory slots with a new
kvm private lock, it is needed beacuse untill now there were cases where
kvm accesses user memory while holding the mmap semaphore.

Signed-off-by: Izik Eidus <izike@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
This commit is contained in:
Izik Eidus
2008-02-10 18:04:15 +02:00
committed by Avi Kivity
parent c7ac679c16
commit 72dc67a696
6 changed files with 75 additions and 40 deletions
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13
arch/x86/kvm/paging_tmpl.h
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@@ -91,7 +91,10 @@ static bool FNAME(cmpxchg_gpte)(struct kvm *kvm,
pt_element_t *table;
struct page *page;
down_read(&current->mm->mmap_sem);
page = gfn_to_page(kvm, table_gfn);
up_read(&current->mm->mmap_sem);
table = kmap_atomic(page, KM_USER0);
ret = CMPXCHG(&table[index], orig_pte, new_pte);
@@ -378,7 +381,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
if (r)
return r;
down_read(&current->mm->mmap_sem);
down_read(&vcpu->kvm->slots_lock);
/*
* Look up the shadow pte for the faulting address.
*/
@@ -392,11 +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);
up_read(&vcpu->kvm->slots_lock);
return 0;
}
down_read(&current->mm->mmap_sem);
page = gfn_to_page(vcpu->kvm, walker.gfn);
up_read(&current->mm->mmap_sem);
spin_lock(&vcpu->kvm->mmu_lock);
kvm_mmu_free_some_pages(vcpu);
@@ -413,14 +418,14 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
*/
if (shadow_pte && is_io_pte(*shadow_pte)) {
spin_unlock(&vcpu->kvm->mmu_lock);
up_read(&current->mm->mmap_sem);
up_read(&vcpu->kvm->slots_lock);
return 1;
}
++vcpu->stat.pf_fixed;
kvm_mmu_audit(vcpu, "post page fault (fixed)");
spin_unlock(&vcpu->kvm->mmu_lock);
up_read(&current->mm->mmap_sem);
up_read(&vcpu->kvm->slots_lock);
return write_pt;
}