KVM: PPC: Book3S: Allocate guest TCEs on demand too

We already allocate hardware TCE tables in multiple levels and skip
intermediate levels when we can, now it is a turn of the KVM TCE tables.
Thankfully these are allocated already in 2 levels.

This moves the table's last level allocation from the creating helper to
kvmppc_tce_put() and kvm_spapr_tce_fault(). Since such allocation cannot
be done in real mode, this creates a virtual mode version of
kvmppc_tce_put() which handles allocations.

This adds kvmppc_rm_ioba_validate() to do an additional test if
the consequent kvmppc_tce_put() needs a page which has not been allocated;
if this is the case, we bail out to virtual mode handlers.

The allocations are protected by a new mutex as kvm->lock is not suitable
for the task because the fault handler is called with the mmap_sem held
but kvmhv_setup_mmu() locks kvm->lock and mmap_sem in the reverse order.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index e6b5bb012ccb..07cefa53222e 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -201,6 +201,8 @@ struct kvmppc_spapr_tce_iommu_table {
 	struct kref kref;
 };
 
+#define TCES_PER_PAGE	(PAGE_SIZE / sizeof(u64))
+
 struct kvmppc_spapr_tce_table {
 	struct list_head list;
 	struct kvm *kvm;
@@ -210,6 +212,7 @@ struct kvmppc_spapr_tce_table {
 	u64 offset;		/* in pages */
 	u64 size;		/* window size in pages */
 	struct list_head iommu_tables;
+	struct mutex alloc_lock;
 	struct page *pages[0];
 };