diff options
| author | Paul Mackerras <paulus@samba.org> | 2012-10-15 01:16:14 +0000 |
|---|---|---|
| committer | Alexander Graf <agraf@suse.de> | 2012-10-30 10:54:54 +0100 |
| commit | 7b444c6710c6c4994e31eb19216ce055836e65c4 (patch) | |
| tree | 52dc3cea624002ca0cfc023b9336676850e6acbd /arch/powerpc/kvm/book3s_hv_rmhandlers.S | |
| parent | 512691d4907d7cf4b8d05c6f8572d1fa60ccec20 (diff) | |
KVM: PPC: Book3S HV: Fix some races in starting secondary threads
Subsequent patches implementing in-kernel XICS emulation will make it
possible for IPIs to arrive at secondary threads at arbitrary times.
This fixes some races in how we start the secondary threads, which
if not fixed could lead to occasional crashes of the host kernel.
This makes sure that (a) we have grabbed all the secondary threads,
and verified that they are no longer in the kernel, before we start
any thread, (b) that the secondary thread loads its vcpu pointer
after clearing the IPI that woke it up (so we don't miss a wakeup),
and (c) that the secondary thread clears its vcpu pointer before
incrementing the nap count. It also removes unnecessary setting
of the vcpu and vcore pointers in the paca in kvmppc_core_vcpu_load.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
Diffstat (limited to 'arch/powerpc/kvm/book3s_hv_rmhandlers.S')
| -rw-r--r-- | arch/powerpc/kvm/book3s_hv_rmhandlers.S | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S index 44b72feaff7..1e90ef6191a 100644 --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S @@ -134,8 +134,11 @@ kvm_start_guest: 27: /* XXX should handle hypervisor maintenance interrupts etc. here */ + /* reload vcpu pointer after clearing the IPI */ + ld r4,HSTATE_KVM_VCPU(r13) + cmpdi r4,0 /* if we have no vcpu to run, go back to sleep */ - beq cr1,kvm_no_guest + beq kvm_no_guest /* were we napping due to cede? */ lbz r0,HSTATE_NAPPING(r13) @@ -1587,6 +1590,10 @@ secondary_too_late: .endr secondary_nap: + /* Clear our vcpu pointer so we don't come back in early */ + li r0, 0 + std r0, HSTATE_KVM_VCPU(r13) + lwsync /* Clear any pending IPI - assume we're a secondary thread */ ld r5, HSTATE_XICS_PHYS(r13) li r7, XICS_XIRR @@ -1612,8 +1619,6 @@ secondary_nap: kvm_no_guest: li r0, KVM_HWTHREAD_IN_NAP stb r0, HSTATE_HWTHREAD_STATE(r13) - li r0, 0 - std r0, HSTATE_KVM_VCPU(r13) li r3, LPCR_PECE0 mfspr r4, SPRN_LPCR |