KVM: MIPS/T&E: Report correct dcache line size

Octeon CPUs don't report the correct dcache line size in CP0_Config1.DL,
so encode the correct value for the guest CP0_Config1.DL based on
cpu_dcache_line_size().
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: David Daney <david.daney@cavium.com>
Cc: Andreas Herrmann <andreas.herrmann@caviumnetworks.com>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org

arch/mips/kvm/trap_emul.c

@@ -12,6 +12,7 @@
 #include <linux/errno.h>
 #include <linux/err.h>
 #include <linux/kvm_host.h>
+#include <linux/log2.h>
 #include <linux/uaccess.h>
 #include <linux/vmalloc.h>
 #include <asm/mmu_context.h>
@@ -644,6 +645,13 @@ static int kvm_trap_emul_vcpu_setup(struct kvm_vcpu *vcpu)
 	/* Read the cache characteristics from the host Config1 Register */
 	config1 = (read_c0_config1() & ~0x7f);
 
+	/* DCache line size not correctly reported in Config1 on Octeon CPUs */
+	if (cpu_dcache_line_size()) {
+		config1 &= ~MIPS_CONF1_DL;
+		config1 |= ((ilog2(cpu_dcache_line_size()) - 1) <<
+			    MIPS_CONF1_DL_SHF) & MIPS_CONF1_DL;
+	}
+
 	/* Set up MMU size */
 	config1 &= ~(0x3f << 25);
 	config1 |= ((KVM_MIPS_GUEST_TLB_SIZE - 1) << 25);