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KVM: MIPS: Update exit handler for VZ 

The general guest exit handler needs a few tweaks for VZ compared to
trap & emulate, which for now are made directly depending on
CONFIG_KVM_MIPS_VZ:

- There is no need to re-enable the hardware page table walker (HTW), as
  it can be left enabled during guest mode operation with VZ.

- There is no need to perform a privilege check, as any guest privilege
  violations should have already been detected by the hardware and
  triggered the appropriate guest exception.

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
This commit is contained in:
James Hogan 2017-03-14 10:15:30 +00:00
parent 60c7aa3320
commit ea1bdbf683
1 changed files with 18 additions and 13 deletions
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31
arch/mips/kvm/mips.c
View File

@ -1230,7 +1230,8 @@ int kvm_mips_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu)
vcpu->mode = OUTSIDE_GUEST_MODE;
/* re-enable HTW before enabling interrupts */
htw_start();
if (!IS_ENABLED(CONFIG_KVM_MIPS_VZ))
htw_start();
/* Set a default exit reason */
run->exit_reason = KVM_EXIT_UNKNOWN;
@ -1248,17 +1249,20 @@ int kvm_mips_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu)
cause, opc, run, vcpu);
trace_kvm_exit(vcpu, exccode);
/*
* Do a privilege check, if in UM most of these exit conditions end up
* causing an exception to be delivered to the Guest Kernel
*/
er = kvm_mips_check_privilege(cause, opc, run, vcpu);
if (er == EMULATE_PRIV_FAIL) {
goto skip_emul;
} else if (er == EMULATE_FAIL) {
run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
ret = RESUME_HOST;
goto skip_emul;
if (!IS_ENABLED(CONFIG_KVM_MIPS_VZ)) {
/*
* Do a privilege check, if in UM most of these exit conditions
* end up causing an exception to be delivered to the Guest
* Kernel
*/
er = kvm_mips_check_privilege(cause, opc, run, vcpu);
if (er == EMULATE_PRIV_FAIL) {
goto skip_emul;
} else if (er == EMULATE_FAIL) {
run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
ret = RESUME_HOST;
goto skip_emul;
}
}
switch (exccode) {
@ -1418,7 +1422,8 @@ skip_emul:
}
/* Disable HTW before returning to guest or host */
htw_stop();
if (!IS_ENABLED(CONFIG_KVM_MIPS_VZ))
htw_stop();
return ret;
}