diff options
| author | Paul Mackerras | 2016-09-15 05:42:52 +0200 |
|---|---|---|
| committer | Paul Mackerras | 2016-09-27 06:41:39 +0200 |
| commit | 88b02cf97bb7e742db3e31671d54177e3e19fd89 (patch) | |
| tree | c46f63021dec7147e31aaff330b259b7df13b0da /arch/powerpc/kvm/book3s_hv_rmhandlers.S | |
| parent | kvm: svm: fix unsigned compare less than zero comparison (diff) | |
| download | kernel-qcow2-linux-88b02cf97bb7e742db3e31671d54177e3e19fd89.tar.gz kernel-qcow2-linux-88b02cf97bb7e742db3e31671d54177e3e19fd89.tar.xz kernel-qcow2-linux-88b02cf97bb7e742db3e31671d54177e3e19fd89.zip | |
KVM: PPC: Book3S: Treat VTB as a per-subcore register, not per-thread
POWER8 has one virtual timebase (VTB) register per subcore, not one
per CPU thread. The HV KVM code currently treats VTB as a per-thread
register, which can lead to spurious soft lockup messages from guests
which use the VTB as the time source for the soft lockup detector.
(CPUs before POWER8 did not have the VTB register.)
For HV KVM, this fixes the problem by making only the primary thread
in each virtual core save and restore the VTB value. With this,
the VTB state becomes part of the kvmppc_vcore structure. This
also means that "piggybacking" of multiple virtual cores onto one
subcore is not possible on POWER8, because then the virtual cores
would share a single VTB register.
PR KVM emulates a VTB register, which is per-vcpu because PR KVM
has no notion of CPU threads or SMT. For PR KVM we move the VTB
state into the kvmppc_vcpu_book3s struct.
Cc: stable@vger.kernel.org # v3.14+
Reported-by: Thomas Huth <thuth@redhat.com>
Tested-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Diffstat (limited to 'arch/powerpc/kvm/book3s_hv_rmhandlers.S')
| -rw-r--r-- | arch/powerpc/kvm/book3s_hv_rmhandlers.S | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S index 7cc924b5eea2..c3c1d1bcfc67 100644 --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S @@ -644,9 +644,11 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_ARCH_207S) 38: BEGIN_FTR_SECTION - /* DPDES is shared between threads */ + /* DPDES and VTB are shared between threads */ ld r8, VCORE_DPDES(r5) + ld r7, VCORE_VTB(r5) mtspr SPRN_DPDES, r8 + mtspr SPRN_VTB, r7 END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) /* Mark the subcore state as inside guest */ @@ -806,10 +808,8 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_207S) mtspr SPRN_CIABR, r7 mtspr SPRN_TAR, r8 ld r5, VCPU_IC(r4) - ld r6, VCPU_VTB(r4) - mtspr SPRN_IC, r5 - mtspr SPRN_VTB, r6 ld r8, VCPU_EBBHR(r4) + mtspr SPRN_IC, r5 mtspr SPRN_EBBHR, r8 ld r5, VCPU_EBBRR(r4) ld r6, VCPU_BESCR(r4) @@ -1334,10 +1334,8 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_207S) stw r6, VCPU_PSPB(r9) std r7, VCPU_FSCR(r9) mfspr r5, SPRN_IC - mfspr r6, SPRN_VTB mfspr r7, SPRN_TAR std r5, VCPU_IC(r9) - std r6, VCPU_VTB(r9) std r7, VCPU_TAR(r9) mfspr r8, SPRN_EBBHR std r8, VCPU_EBBHR(r9) @@ -1564,9 +1562,11 @@ kvmhv_switch_to_host: isync BEGIN_FTR_SECTION - /* DPDES is shared between threads */ + /* DPDES and VTB are shared between threads */ mfspr r7, SPRN_DPDES + mfspr r8, SPRN_VTB std r7, VCORE_DPDES(r5) + std r8, VCORE_VTB(r5) /* clear DPDES so we don't get guest doorbells in the host */ li r8, 0 mtspr SPRN_DPDES, r8 |