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KVM: introduce kvm->srcu and convert kvm_set_memory_region to SRCU update

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Use two steps for memslot deletion: mark the slot invalid (which stops
instantiation of new shadow pages for that slot, but allows destruction),
then instantiate the new empty slot.

Also simplifies kvm_handle_hva locking.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Marcelo Tosatti
2009-12-23 14:35:21 -02:00
parent 3ad26d8139
commit bc6678a33d
8 changed files with 136 additions and 64 deletions
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28
arch/x86/kvm/mmu.c
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@@ -29,6 +29,7 @@
#include <linux/swap.h>
#include <linux/hugetlb.h>
#include <linux/compiler.h>
#include <linux/srcu.h>
#include <asm/page.h>
#include <asm/cmpxchg.h>
@@ -807,21 +808,15 @@ static int kvm_handle_hva(struct kvm *kvm, unsigned long hva,
{
int i, j;
int retval = 0;
struct kvm_memslots *slots = kvm->memslots;
struct kvm_memslots *slots;
slots = rcu_dereference(kvm->memslots);
/*
* If mmap_sem isn't taken, we can look the memslots with only
* the mmu_lock by skipping over the slots with userspace_addr == 0.
*/
for (i = 0; i < slots->nmemslots; i++) {
struct kvm_memory_slot *memslot = &slots->memslots[i];
unsigned long start = memslot->userspace_addr;
unsigned long end;
/* mmu_lock protects userspace_addr */
if (!start)
continue;
end = start + (memslot->npages << PAGE_SHIFT);
if (hva >= start && hva < end) {
gfn_t gfn_offset = (hva - start) >> PAGE_SHIFT;
@@ -1617,7 +1612,7 @@ static void mmu_unshadow(struct kvm *kvm, gfn_t gfn)
static void page_header_update_slot(struct kvm *kvm, void *pte, gfn_t gfn)
{
int slot = memslot_id(kvm, gfn_to_memslot(kvm, gfn));
int slot = memslot_id(kvm, gfn);
struct kvm_mmu_page *sp = page_header(__pa(pte));
__set_bit(slot, sp->slot_bitmap);
@@ -3021,9 +3016,11 @@ unsigned int kvm_mmu_calculate_mmu_pages(struct kvm *kvm)
int i;
unsigned int nr_mmu_pages;
unsigned int nr_pages = 0;
struct kvm_memslots *slots;
for (i = 0; i < kvm->memslots->nmemslots; i++)
nr_pages += kvm->memslots->memslots[i].npages;
slots = rcu_dereference(kvm->memslots);
for (i = 0; i < slots->nmemslots; i++)
nr_pages += slots->memslots[i].npages;
nr_mmu_pages = nr_pages * KVM_PERMILLE_MMU_PAGES / 1000;
nr_mmu_pages = max(nr_mmu_pages,
@@ -3293,10 +3290,12 @@ static void audit_mappings(struct kvm_vcpu *vcpu)
static int count_rmaps(struct kvm_vcpu *vcpu)
{
int nmaps = 0;
int i, j, k;
int i, j, k, idx;
idx = srcu_read_lock(&kvm->srcu);
slots = rcu_dereference(kvm->memslots);
for (i = 0; i < KVM_MEMORY_SLOTS; ++i) {
struct kvm_memory_slot *m = &vcpu->kvm->memslots->memslots[i];
struct kvm_memory_slot *m = &slots->memslots[i];
struct kvm_rmap_desc *d;
for (j = 0; j < m->npages; ++j) {
@@ -3319,6 +3318,7 @@ static int count_rmaps(struct kvm_vcpu *vcpu)
}
}
}
srcu_read_unlock(&kvm->srcu, idx);
return nmaps;
}