From: Paul Mackerras Date: Thu, 15 Sep 2016 03:42:52 +0000 (+1000) Subject: KVM: PPC: Book3S: Treat VTB as a per-subcore register, not per-thread X-Git-Tag: v3.16.40~235 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=469a46b41efd3fa7656f31f2bae2674e8e579f06;p=thirdparty%2Fkernel%2Fstable.git KVM: PPC: Book3S: Treat VTB as a per-subcore register, not per-thread commit 88b02cf97bb7e742db3e31671d54177e3e19fd89 upstream. 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. Reported-by: Thomas Huth Tested-by: Thomas Huth Signed-off-by: Paul Mackerras [bwh: Backported to 3.16: - Adjust filenames, context - Drop changes to kvmppc_core_emulate_mfspr_pr(), can_piggyback_subcore(), kvmppc_copy_from_svcpu()] Signed-off-by: Ben Hutchings --- diff --git a/arch/powerpc/include/asm/kvm_book3s.h b/arch/powerpc/include/asm/kvm_book3s.h index f52f65694527e..0689091f95055 100644 --- a/arch/powerpc/include/asm/kvm_book3s.h +++ b/arch/powerpc/include/asm/kvm_book3s.h @@ -83,6 +83,7 @@ struct kvmppc_vcpu_book3s { u64 sdr1; u64 hior; u64 msr_mask; + u64 vtb; u64 purr_offset; u64 spurr_offset; #ifdef CONFIG_PPC_BOOK3S_32 diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h index bb66d8b8efdf0..2149dbcf89312 100644 --- a/arch/powerpc/include/asm/kvm_host.h +++ b/arch/powerpc/include/asm/kvm_host.h @@ -305,6 +305,7 @@ struct kvmppc_vcore { u32 arch_compat; ulong pcr; ulong dpdes; /* doorbell state (POWER8) */ + ulong vtb; /* virtual timebase */ }; #define VCORE_ENTRY_COUNT(vc) ((vc)->entry_exit_count & 0xff) @@ -462,7 +463,6 @@ struct kvm_vcpu_arch { ulong purr; ulong spurr; ulong ic; - ulong vtb; ulong dscr; ulong amr; ulong uamor; diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c index f5995a912213f..88abea8898765 100644 --- a/arch/powerpc/kernel/asm-offsets.c +++ b/arch/powerpc/kernel/asm-offsets.c @@ -506,7 +506,6 @@ int main(void) DEFINE(VCPU_PURR, offsetof(struct kvm_vcpu, arch.purr)); DEFINE(VCPU_SPURR, offsetof(struct kvm_vcpu, arch.spurr)); DEFINE(VCPU_IC, offsetof(struct kvm_vcpu, arch.ic)); - DEFINE(VCPU_VTB, offsetof(struct kvm_vcpu, arch.vtb)); DEFINE(VCPU_DSCR, offsetof(struct kvm_vcpu, arch.dscr)); DEFINE(VCPU_AMR, offsetof(struct kvm_vcpu, arch.amr)); DEFINE(VCPU_UAMOR, offsetof(struct kvm_vcpu, arch.uamor)); @@ -560,6 +559,7 @@ int main(void) DEFINE(VCORE_LPCR, offsetof(struct kvmppc_vcore, lpcr)); DEFINE(VCORE_PCR, offsetof(struct kvmppc_vcore, pcr)); DEFINE(VCORE_DPDES, offsetof(struct kvmppc_vcore, dpdes)); + DEFINE(VCORE_VTB, offsetof(struct kvmppc_vcore, vtb)); DEFINE(VCPU_SLB_E, offsetof(struct kvmppc_slb, orige)); DEFINE(VCPU_SLB_V, offsetof(struct kvmppc_slb, origv)); DEFINE(VCPU_SLB_SIZE, sizeof(struct kvmppc_slb)); diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 89d4ebd8152b4..a416b6bb0d6a2 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -909,7 +909,7 @@ static int kvmppc_get_one_reg_hv(struct kvm_vcpu *vcpu, u64 id, *val = get_reg_val(id, vcpu->arch.ic); break; case KVM_REG_PPC_VTB: - *val = get_reg_val(id, vcpu->arch.vtb); + *val = get_reg_val(id, vcpu->arch.vcore->vtb); break; case KVM_REG_PPC_CSIGR: *val = get_reg_val(id, vcpu->arch.csigr); @@ -1110,7 +1110,7 @@ static int kvmppc_set_one_reg_hv(struct kvm_vcpu *vcpu, u64 id, vcpu->arch.ic = set_reg_val(id, *val); break; case KVM_REG_PPC_VTB: - vcpu->arch.vtb = set_reg_val(id, *val); + vcpu->arch.vcore->vtb = set_reg_val(id, *val); break; case KVM_REG_PPC_CSIGR: vcpu->arch.csigr = set_reg_val(id, *val); diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S index 2f0c1394efa8d..ab69a5f242d1c 100644 --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S @@ -457,9 +457,11 @@ 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) li r0,1 @@ -736,10 +738,8 @@ 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) @@ -1147,10 +1147,8 @@ 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) @@ -1442,9 +1440,11 @@ secondary_too_late: 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 diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c index 66b7afec250fa..e587264c2e8ce 100644 --- a/arch/powerpc/kvm/book3s_pr.c +++ b/arch/powerpc/kvm/book3s_pr.c @@ -1232,6 +1232,9 @@ static int kvmppc_get_one_reg_pr(struct kvm_vcpu *vcpu, u64 id, case KVM_REG_PPC_HIOR: *val = get_reg_val(id, to_book3s(vcpu)->hior); break; + case KVM_REG_PPC_VTB: + *val = get_reg_val(id, to_book3s(vcpu)->vtb); + break; case KVM_REG_PPC_LPCR: case KVM_REG_PPC_LPCR_64: /* @@ -1268,6 +1271,9 @@ static int kvmppc_set_one_reg_pr(struct kvm_vcpu *vcpu, u64 id, to_book3s(vcpu)->hior = set_reg_val(id, *val); to_book3s(vcpu)->hior_explicit = true; break; + case KVM_REG_PPC_VTB: + to_book3s(vcpu)->vtb = set_reg_val(id, *val); + break; case KVM_REG_PPC_LPCR: case KVM_REG_PPC_LPCR_64: kvmppc_set_lpcr_pr(vcpu, set_reg_val(id, *val));