KVM: introduce kvm->srcu and convert kvm_set_memory_region to SRCU update
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>
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 81f84d3..f8bf42a 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -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 @@
{
int i, j;
int retval = 0;
- struct kvm_memslots *slots = kvm->memslots;
+ struct kvm_memslots *slots;
- /*
- * 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.
- */
+ slots = rcu_dereference(kvm->memslots);
+
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 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 @@
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 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 @@
}
}
}
+ srcu_read_unlock(&kvm->srcu, idx);
return nmaps;
}
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 1869879..f1cae7d 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1503,7 +1503,11 @@
static gva_t rmode_tss_base(struct kvm *kvm)
{
if (!kvm->arch.tss_addr) {
- gfn_t base_gfn = kvm->memslots->memslots[0].base_gfn +
+ struct kvm_memslots *slots;
+ gfn_t base_gfn;
+
+ slots = rcu_dereference(kvm->memslots);
+ base_gfn = kvm->memslots->memslots[0].base_gfn +
kvm->memslots->memslots[0].npages - 3;
return base_gfn << PAGE_SHIFT;
}