KVM: PPC: Implement MMU notifiers for Book3S HV guests
This adds the infrastructure to enable us to page out pages underneath
a Book3S HV guest, on processors that support virtualized partition
memory, that is, POWER7. Instead of pinning all the guest's pages,
we now look in the host userspace Linux page tables to find the
mapping for a given guest page. Then, if the userspace Linux PTE
gets invalidated, kvm_unmap_hva() gets called for that address, and
we replace all the guest HPTEs that refer to that page with absent
HPTEs, i.e. ones with the valid bit clear and the HPTE_V_ABSENT bit
set, which will cause an HDSI when the guest tries to access them.
Finally, the page fault handler is extended to reinstantiate the
guest HPTE when the guest tries to access a page which has been paged
out.
Since we can't intercept the guest DSI and ISI interrupts on PPC970,
we still have to pin all the guest pages on PPC970. We have a new flag,
kvm->arch.using_mmu_notifiers, that indicates whether we can page
guest pages out. If it is not set, the MMU notifier callbacks do
nothing and everything operates as before.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/powerpc/include/asm/kvm_book3s_64.h b/arch/powerpc/include/asm/kvm_book3s_64.h
index 79dc37f..c21e46d 100644
--- a/arch/powerpc/include/asm/kvm_book3s_64.h
+++ b/arch/powerpc/include/asm/kvm_book3s_64.h
@@ -136,6 +136,37 @@
return (wimg & (HPTE_R_W | HPTE_R_I)) == io_type;
}
+/*
+ * Lock and read a linux PTE. If it's present and writable, atomically
+ * set dirty and referenced bits and return the PTE, otherwise return 0.
+ */
+static inline pte_t kvmppc_read_update_linux_pte(pte_t *p)
+{
+ pte_t pte, tmp;
+
+ /* wait until _PAGE_BUSY is clear then set it atomically */
+ __asm__ __volatile__ (
+ "1: ldarx %0,0,%3\n"
+ " andi. %1,%0,%4\n"
+ " bne- 1b\n"
+ " ori %1,%0,%4\n"
+ " stdcx. %1,0,%3\n"
+ " bne- 1b"
+ : "=&r" (pte), "=&r" (tmp), "=m" (*p)
+ : "r" (p), "i" (_PAGE_BUSY)
+ : "cc");
+
+ if (pte_present(pte)) {
+ pte = pte_mkyoung(pte);
+ if (pte_write(pte))
+ pte = pte_mkdirty(pte);
+ }
+
+ *p = pte; /* clears _PAGE_BUSY */
+
+ return pte;
+}
+
/* Return HPTE cache control bits corresponding to Linux pte bits */
static inline unsigned long hpte_cache_bits(unsigned long pte_val)
{