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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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24
arch/x86/kvm/mmu.c
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@@ -876,11 +876,18 @@ static void page_header_update_slot(struct kvm *kvm, void *pte, gfn_t gfn)
struct page *gva_to_page(struct kvm_vcpu *vcpu, gva_t gva)
{
struct page *page;
gpa_t gpa = vcpu->arch.mmu.gva_to_gpa(vcpu, gva);
if (gpa == UNMAPPED_GVA)
return NULL;
return gfn_to_page(vcpu->kvm, gpa >> PAGE_SHIFT);
down_read(&current->mm->mmap_sem);
page = gfn_to_page(vcpu->kvm, gpa >> PAGE_SHIFT);
up_read(&current->mm->mmap_sem);
return page;
}
static void mmu_set_spte(struct kvm_vcpu *vcpu, u64 *shadow_pte,
@@ -1020,15 +1027,18 @@ static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, int write, gfn_t gfn)
struct page *page;
down_read(&vcpu->kvm->slots_lock);
down_read(&current->mm->mmap_sem);
page = gfn_to_page(vcpu->kvm, gfn);
up_read(&current->mm->mmap_sem);
spin_lock(&vcpu->kvm->mmu_lock);
kvm_mmu_free_some_pages(vcpu);
r = __nonpaging_map(vcpu, v, write, gfn, page);
spin_unlock(&vcpu->kvm->mmu_lock);
up_read(&current->mm->mmap_sem);
up_read(&vcpu->kvm->slots_lock);
return r;
}
@@ -1362,6 +1372,7 @@ static void mmu_guess_page_from_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
gfn_t gfn;
int r;
u64 gpte = 0;
struct page *page;
if (bytes != 4 && bytes != 8)
return;
@@ -1389,6 +1400,11 @@ static void mmu_guess_page_from_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
if (!is_present_pte(gpte))
return;
gfn = (gpte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT;
down_read(&current->mm->mmap_sem);
page = gfn_to_page(vcpu->kvm, gfn);
up_read(&current->mm->mmap_sem);
vcpu->arch.update_pte.gfn = gfn;
vcpu->arch.update_pte.page = gfn_to_page(vcpu->kvm, gfn);
}
@@ -1496,9 +1512,9 @@ int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva)
gpa_t gpa;
int r;
down_read(&current->mm->mmap_sem);
down_read(&vcpu->kvm->slots_lock);
gpa = vcpu->arch.mmu.gva_to_gpa(vcpu, gva);
up_read(&current->mm->mmap_sem);
up_read(&vcpu->kvm->slots_lock);
spin_lock(&vcpu->kvm->mmu_lock);
r = kvm_mmu_unprotect_page(vcpu->kvm, gpa >> PAGE_SHIFT);