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authorTakuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>2012-07-02 17:55:48 +0900
committerMarcelo Tosatti <mtosatti@redhat.com>2012-07-18 16:55:04 -0300
commit84504ef38673fa021b3d8f3da2b79cf878b33315 (patch)
tree55c6238ebfa17790dad0136493b7b0f375828ace /arch/x86/kvm/mmu.c
parentd19a748b1c42b133e9263e9023c1d162efa6f4ad (diff)
downloadblackbird-op-linux-84504ef38673fa021b3d8f3da2b79cf878b33315.tar.gz
blackbird-op-linux-84504ef38673fa021b3d8f3da2b79cf878b33315.zip
KVM: MMU: Make kvm_handle_hva() handle range of addresses
When guest's memory is backed by THP pages, MMU notifier needs to call kvm_unmap_hva(), which in turn leads to kvm_handle_hva(), in a loop to invalidate a range of pages which constitute one huge page: for each page for each memslot if page is in memslot unmap using rmap This means although every page in that range is expected to be found in the same memslot, we are forced to check unrelated memslots many times. If the guest has more memslots, the situation will become worse. Furthermore, if the range does not include any pages in the guest's memory, the loop over the pages will just consume extra time. This patch, together with the following patches, solves this problem by introducing kvm_handle_hva_range() which makes the loop look like this: for each memslot for each page in memslot unmap using rmap In this new processing, the actual work is converted to a loop over rmap which is much more cache friendly than before. Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp> Cc: Alexander Graf <agraf@suse.de> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Diffstat (limited to 'arch/x86/kvm/mmu.c')
-rw-r--r--arch/x86/kvm/mmu.c42
1 files changed, 32 insertions, 10 deletions
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 170a632d9d34..7235b0c9587d 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1259,10 +1259,13 @@ static int kvm_set_pte_rmapp(struct kvm *kvm, unsigned long *rmapp,
return 0;
}
-static int kvm_handle_hva(struct kvm *kvm, unsigned long hva,
- unsigned long data,
- int (*handler)(struct kvm *kvm, unsigned long *rmapp,
- unsigned long data))
+static int kvm_handle_hva_range(struct kvm *kvm,
+ unsigned long start,
+ unsigned long end,
+ unsigned long data,
+ int (*handler)(struct kvm *kvm,
+ unsigned long *rmapp,
+ unsigned long data))
{
int j;
int ret;
@@ -1273,13 +1276,22 @@ static int kvm_handle_hva(struct kvm *kvm, unsigned long hva,
slots = kvm_memslots(kvm);
kvm_for_each_memslot(memslot, slots) {
- unsigned long start = memslot->userspace_addr;
- unsigned long end;
+ unsigned long hva_start, hva_end;
+ gfn_t gfn, gfn_end;
- end = start + (memslot->npages << PAGE_SHIFT);
- if (hva >= start && hva < end) {
- gfn_t gfn = hva_to_gfn_memslot(hva, memslot);
+ hva_start = max(start, memslot->userspace_addr);
+ hva_end = min(end, memslot->userspace_addr +
+ (memslot->npages << PAGE_SHIFT));
+ if (hva_start >= hva_end)
+ continue;
+ /*
+ * {gfn(page) | page intersects with [hva_start, hva_end)} =
+ * {gfn, gfn+1, ..., gfn_end-1}.
+ */
+ gfn = hva_to_gfn_memslot(hva_start, memslot);
+ gfn_end = hva_to_gfn_memslot(hva_end + PAGE_SIZE - 1, memslot);
+ for (; gfn < gfn_end; ++gfn) {
ret = 0;
for (j = PT_PAGE_TABLE_LEVEL;
@@ -1289,7 +1301,9 @@ static int kvm_handle_hva(struct kvm *kvm, unsigned long hva,
rmapp = __gfn_to_rmap(gfn, j, memslot);
ret |= handler(kvm, rmapp, data);
}
- trace_kvm_age_page(hva, memslot, ret);
+ trace_kvm_age_page(memslot->userspace_addr +
+ (gfn - memslot->base_gfn) * PAGE_SIZE,
+ memslot, ret);
retval |= ret;
}
}
@@ -1297,6 +1311,14 @@ static int kvm_handle_hva(struct kvm *kvm, unsigned long hva,
return retval;
}
+static int kvm_handle_hva(struct kvm *kvm, unsigned long hva,
+ unsigned long data,
+ int (*handler)(struct kvm *kvm, unsigned long *rmapp,
+ unsigned long data))
+{
+ return kvm_handle_hva_range(kvm, hva, hva + 1, data, handler);
+}
+
int kvm_unmap_hva(struct kvm *kvm, unsigned long hva)
{
return kvm_handle_hva(kvm, hva, 0, kvm_unmap_rmapp);
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