diff options
| author | James Hogan <james.hogan@imgtec.com> | 2016-05-06 14:36:18 +0100 |
|---|---|---|
| committer | Ralf Baechle <ralf@linux-mips.org> | 2016-05-13 14:02:18 +0200 |
| commit | 5fb59fd2e7f7ee6bfc20ab9c0ef82e33c0057be5 (patch) | |
| tree | b3c604c2b4705e6e7317620186c00dd0ba7449ed | |
| parent | 97b921087fa76b1b0b2a20ae70d0e8b6d394c4ea (diff) | |
| download | linux-5fb59fd2e7f7ee6bfc20ab9c0ef82e33c0057be5.tar.gz | |
MIPS: KVM/locore.S: Don't preserve host ASID around vcpu_run
MIPS KVM uses different ASIDs for guest execution than for the host. The host ASID is saved on the stack when entering the guest with __kvm_mips_vcpu_run(), and restored again before returning back to the caller (exit to userland). - This does not take into account that pre-emption may have taken place during that time, which may have started a new ASID cycle and resulted in that process' ASID being invalidated and reused. - This does not take into account that the process may have migrated to a different CPU during that time, with a different ASID assignment since they are managed per-CPU. - It is actually redundant, since the host ASID will be restored correctly by kvm_arch_vcpu_put(), which is called almost immediately after kvm_arch_vcpu_ioctl_run() returns. Therefore drop this code from locore.S Signed-off-by: James Hogan <james.hogan@imgtec.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: Paul Burton <paul.burton@imgtec.com> Cc: linux-mips@linux-mips.org Cc: kvm@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/13206/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
| -rw-r--r-- | arch/mips/kvm/locore.S | 12 |
1 files changed, 0 insertions, 12 deletions
diff --git a/arch/mips/kvm/locore.S b/arch/mips/kvm/locore.S index 81687ab1b523..c24facc85357 100644 --- a/arch/mips/kvm/locore.S +++ b/arch/mips/kvm/locore.S @@ -32,7 +32,6 @@ EXPORT(x); /* Overload, Danger Will Robinson!! */ -#define PT_HOST_ASID PT_BVADDR #define PT_HOST_USERLOCAL PT_EPC #define CP0_DDATA_LO $28,3 @@ -104,11 +103,6 @@ FEXPORT(__kvm_mips_vcpu_run) mfc0 v0, CP0_STATUS LONG_S v0, PT_STATUS(k1) - /* Save host ASID, shove it into the BVADDR location */ - mfc0 v1, CP0_ENTRYHI - andi v1, 0xff - LONG_S v1, PT_HOST_ASID(k1) - /* Save DDATA_LO, will be used to store pointer to vcpu */ mfc0 v1, CP0_DDATA_LO LONG_S v1, PT_HOST_USERLOCAL(k1) @@ -551,12 +545,6 @@ __kvm_mips_return_to_host: LONG_L k0, PT_HOST_USERLOCAL(k1) mtc0 k0, CP0_DDATA_LO - /* Restore host ASID */ - LONG_L k0, PT_HOST_ASID(sp) - andi k0, 0xff - mtc0 k0,CP0_ENTRYHI - ehb - /* Load context saved on the host stack */ LONG_L $0, PT_R0(k1) LONG_L $1, PT_R1(k1) |