KVM: MIPS/MMU: Convert guest physical map to page table

Current guest physical memory is mapped to host physical addresses using
a single linear array (guest_pmap of length guest_pmap_npages). This was
only really meant to be temporary, and isn't sparse, so its wasteful of
memory. A small amount of RAM at GPA 0 and a small boot exception vector
at GPA 0x1fc00000 cannot be represented without a full 128KiB guest_pmap
allocation (MIPS32 with 16KiB pages), which is one reason why QEMU
currently runs its boot code at the top of RAM instead of the usual boot
exception vector address.

Instead use the existing infrastructure for host virtual page table
management to allocate a page table for guest physical memory too. This
should be sufficient for now, assuming the size of physical memory
doesn't exceed the size of virtual memory. It may need extending in
future to handle XPA (eXtended Physical Addressing) in 32-bit guests, as
supported by VZ guests on P5600.

Some of this code is based loosely on Cavium's VZ KVM implementation.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org

1 files changed, 4 insertions, 3 deletions

diff --git a/arch/mips/include/asm/kvm_host.h b/arch/mips/include/asm/kvm_host.h
index 17c5e53..a046579 100644
--- a/arch/mips/include/asm/kvm_host.h
+++ b/arch/mips/include/asm/kvm_host.h
@@ -153,9 +153,8 @@ struct kvm_arch_memory_slot {
 };
 
 struct kvm_arch {
-	/* Guest GVA->HPA page table */
-	unsigned long *guest_pmap;
-	unsigned long guest_pmap_npages;
+	/* Guest physical mm */
+	struct mm_struct gpa_mm;
 };
 
 #define N_MIPS_COPROC_REGS	32
@@ -636,6 +635,8 @@ enum kvm_mips_flush {
 	KMF_GPA		= 0x2,
 };
 void kvm_mips_flush_gva_pt(pgd_t *pgd, enum kvm_mips_flush flags);
+bool kvm_mips_flush_gpa_pt(struct kvm *kvm, gfn_t start_gfn, gfn_t end_gfn);
+pgd_t *kvm_pgd_alloc(void);
 void kvm_mmu_free_memory_caches(struct kvm_vcpu *vcpu);
 void kvm_trap_emul_invalidate_gva(struct kvm_vcpu *vcpu, unsigned long addr,
 				  bool user);