MIPS: KVM: Restore host EBase from ebase variable

The host kernel's exception vector base address is currently saved in
the VCPU structure at creation time, and restored on a guest exit.
However it doesn't change and can already be easily accessed from the
'ebase' variable (arch/mips/kernel/traps.c), so drop the host_ebase
member of kvm_vcpu_arch, export the 'ebase' variable to modules and load
from there instead.

This does result in a single extra instruction (lui) on the guest exit
path, but simplifies the code a bit and removes the redundant storage of
the host exception base address.

Credit for the idea goes to 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
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 0 insertions, 1 deletions

diff --git a/arch/mips/kernel/asm-offsets.c b/arch/mips/kernel/asm-offsets.c
index 4208088..a1263d1 100644
--- a/arch/mips/kernel/asm-offsets.c
+++ b/arch/mips/kernel/asm-offsets.c
@@ -355,7 +355,6 @@ void output_kvm_defines(void)
 	OFFSET(VCPU_RUN, kvm_vcpu, run);
 	OFFSET(VCPU_HOST_ARCH, kvm_vcpu, arch);
 
-	OFFSET(VCPU_HOST_EBASE, kvm_vcpu_arch, host_ebase);
 	OFFSET(VCPU_GUEST_EBASE, kvm_vcpu_arch, guest_ebase);
 
 	OFFSET(VCPU_HOST_STACK, kvm_vcpu_arch, host_stack);