From 2f2724630f7a8d582470f03ee56b96746767d270 Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Mon, 22 May 2017 16:25:14 +1000 Subject: KVM: PPC: Book3S HV: Cope with host using large decrementer mode POWER9 introduces a new mode for the decrementer register, called large decrementer mode, in which the decrementer counter is 56 bits wide rather than 32, and reads are sign-extended rather than zero-extended. For the decrementer, this new mode is optional and controlled by a bit in the LPCR. The hypervisor decrementer (HDEC) is 56 bits wide on POWER9 and has no mode control. Since KVM code reads and writes the decrementer and hypervisor decrementer registers in a few places, it needs to be aware of the need to treat the decrementer value as a 64-bit quantity, and only do a 32-bit sign extension when large decrementer mode is not in effect. Similarly, the HDEC should always be treated as a 64-bit quantity on POWER9. We define a new EXTEND_HDEC macro to encapsulate the feature test for POWER9 and the sign extension. To enable the sign extension to be removed in large decrementer mode, we test the LPCR_LD bit in the host LPCR image stored in the struct kvm for the guest. If is set then large decrementer mode is enabled and the sign extension should be skipped. This is partly based on an earlier patch by Oliver O'Halloran. Cc: stable@vger.kernel.org # v4.10+ Signed-off-by: Paul Mackerras --- arch/powerpc/kvm/book3s_hv_interrupts.S | 12 +++++++++++- arch/powerpc/kvm/book3s_hv_rmhandlers.S | 23 +++++++++++++++++------ 2 files changed, 28 insertions(+), 7 deletions(-) (limited to 'arch') diff --git a/arch/powerpc/kvm/book3s_hv_interrupts.S b/arch/powerpc/kvm/book3s_hv_interrupts.S index 0fdc4a28970b..404deb512844 100644 --- a/arch/powerpc/kvm/book3s_hv_interrupts.S +++ b/arch/powerpc/kvm/book3s_hv_interrupts.S @@ -121,10 +121,20 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) * Put whatever is in the decrementer into the * hypervisor decrementer. */ +BEGIN_FTR_SECTION + ld r5, HSTATE_KVM_VCORE(r13) + ld r6, VCORE_KVM(r5) + ld r9, KVM_HOST_LPCR(r6) + andis. r9, r9, LPCR_LD@h +END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300) mfspr r8,SPRN_DEC mftb r7 - mtspr SPRN_HDEC,r8 +BEGIN_FTR_SECTION + /* On POWER9, don't sign-extend if host LPCR[LD] bit is set */ + bne 32f +END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300) extsw r8,r8 +32: mtspr SPRN_HDEC,r8 add r8,r8,r7 std r8,HSTATE_DECEXP(r13) diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S index bdb3f76ceb6b..e390b383b4d6 100644 --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S @@ -32,6 +32,12 @@ #include #include +/* Sign-extend HDEC if not on POWER9 */ +#define EXTEND_HDEC(reg) \ +BEGIN_FTR_SECTION; \ + extsw reg, reg; \ +END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300) + #define VCPU_GPRS_TM(reg) (((reg) * ULONG_SIZE) + VCPU_GPR_TM) /* Values in HSTATE_NAPPING(r13) */ @@ -214,6 +220,8 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) kvmppc_primary_no_guest: /* We handle this much like a ceded vcpu */ /* put the HDEC into the DEC, since HDEC interrupts don't wake us */ + /* HDEC may be larger than DEC for arch >= v3.00, but since the */ + /* HDEC value came from DEC in the first place, it will fit */ mfspr r3, SPRN_HDEC mtspr SPRN_DEC, r3 /* @@ -295,8 +303,9 @@ kvm_novcpu_wakeup: /* See if our timeslice has expired (HDEC is negative) */ mfspr r0, SPRN_HDEC + EXTEND_HDEC(r0) li r12, BOOK3S_INTERRUPT_HV_DECREMENTER - cmpwi r0, 0 + cmpdi r0, 0 blt kvm_novcpu_exit /* Got an IPI but other vcpus aren't yet exiting, must be a latecomer */ @@ -390,8 +399,8 @@ kvm_secondary_got_guest: lbz r4, HSTATE_PTID(r13) cmpwi r4, 0 bne 63f - lis r6, 0x7fff - ori r6, r6, 0xffff + LOAD_REG_ADDR(r6, decrementer_max) + ld r6, 0(r6) mtspr SPRN_HDEC, r6 /* and set per-LPAR registers, if doing dynamic micro-threading */ ld r6, HSTATE_SPLIT_MODE(r13) @@ -968,7 +977,8 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_ARCH_300) /* Check if HDEC expires soon */ mfspr r3, SPRN_HDEC - cmpwi r3, 512 /* 1 microsecond */ + EXTEND_HDEC(r3) + cmpdi r3, 512 /* 1 microsecond */ blt hdec_soon #ifdef CONFIG_KVM_XICS @@ -2366,12 +2376,13 @@ END_FTR_SECTION_IFSET(CPU_FTR_TM) mfspr r3, SPRN_DEC mfspr r4, SPRN_HDEC mftb r5 - cmpw r3, r4 + extsw r3, r3 + EXTEND_HDEC(r4) + cmpd r3, r4 ble 67f mtspr SPRN_DEC, r4 67: /* save expiry time of guest decrementer */ - extsw r3, r3 add r3, r3, r5 ld r4, HSTATE_KVM_VCPU(r13) ld r5, HSTATE_KVM_VCORE(r13) -- cgit 1.4.1 From ca8efa1df1d15a1795a2da57f9f6aada6ed6b946 Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Tue, 6 Jun 2017 16:47:22 +1000 Subject: KVM: PPC: Book3S HV: Context-switch EBB registers properly This adds code to save the values of three SPRs (special-purpose registers) used by userspace to control event-based branches (EBBs), which are essentially interrupts that get delivered directly to userspace. These registers are loaded up with guest values when entering the guest, and their values are saved when exiting the guest, but we were not saving the host values and restoring them before going back to userspace. On POWER8 this would only affect userspace programs which explicitly request the use of EBBs and also use the KVM_RUN ioctl, since the only source of EBBs on POWER8 is the PMU, and there is an explicit enable bit in the PMU registers (and those PMU registers do get properly context-switched between host and guest). On POWER9 there is provision for externally-generated EBBs, and these are not subject to the control in the PMU registers. Since these registers only affect userspace, we can save them when we first come in from userspace and restore them before returning to userspace, rather than saving/restoring the host values on every guest entry/exit. Similarly, we don't need to worry about their values on offline secondary threads since they execute in the context of the idle task, which never executes in userspace. Fixes: b005255e12a3 ("KVM: PPC: Book3S HV: Context-switch new POWER8 SPRs", 2014-01-08) Cc: stable@vger.kernel.org # v3.14+ Signed-off-by: Paul Mackerras --- arch/powerpc/kvm/book3s_hv.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'arch') diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 42b7a4fd57d9..400a5992b121 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -2907,6 +2907,7 @@ static int kvmppc_vcpu_run_hv(struct kvm_run *run, struct kvm_vcpu *vcpu) { int r; int srcu_idx; + unsigned long ebb_regs[3] = {}; /* shut up GCC */ if (!vcpu->arch.sane) { run->exit_reason = KVM_EXIT_INTERNAL_ERROR; @@ -2934,6 +2935,13 @@ static int kvmppc_vcpu_run_hv(struct kvm_run *run, struct kvm_vcpu *vcpu) flush_all_to_thread(current); + /* Save userspace EBB register values */ + if (cpu_has_feature(CPU_FTR_ARCH_207S)) { + ebb_regs[0] = mfspr(SPRN_EBBHR); + ebb_regs[1] = mfspr(SPRN_EBBRR); + ebb_regs[2] = mfspr(SPRN_BESCR); + } + vcpu->arch.wqp = &vcpu->arch.vcore->wq; vcpu->arch.pgdir = current->mm->pgd; vcpu->arch.state = KVMPPC_VCPU_BUSY_IN_HOST; @@ -2960,6 +2968,13 @@ static int kvmppc_vcpu_run_hv(struct kvm_run *run, struct kvm_vcpu *vcpu) } } while (is_kvmppc_resume_guest(r)); + /* Restore userspace EBB register values */ + if (cpu_has_feature(CPU_FTR_ARCH_207S)) { + mtspr(SPRN_EBBHR, ebb_regs[0]); + mtspr(SPRN_EBBRR, ebb_regs[1]); + mtspr(SPRN_BESCR, ebb_regs[2]); + } + out: vcpu->arch.state = KVMPPC_VCPU_NOTREADY; atomic_dec(&vcpu->kvm->arch.vcpus_running); -- cgit 1.4.1 From 4c3bb4ccd074e1a0552078c0bf94c662367a1658 Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Thu, 15 Jun 2017 15:43:17 +1000 Subject: KVM: PPC: Book3S HV: Restore critical SPRs to host values on guest exit This restores several special-purpose registers (SPRs) to sane values on guest exit that were missed before. TAR and VRSAVE are readable and writable by userspace, and we need to save and restore them to prevent the guest from potentially affecting userspace execution (not that TAR or VRSAVE are used by any known program that run uses the KVM_RUN ioctl). We save/restore these in kvmppc_vcpu_run_hv() rather than on every guest entry/exit. FSCR affects userspace execution in that it can prohibit access to certain facilities by userspace. We restore it to the normal value for the task on exit from the KVM_RUN ioctl. IAMR is normally 0, and is restored to 0 on guest exit. However, with a radix host on POWER9, it is set to a value that prevents the kernel from executing user-accessible memory. On POWER9, we save IAMR on guest entry and restore it on guest exit to the saved value rather than 0. On POWER8 we continue to set it to 0 on guest exit. PSPB is normally 0. We restore it to 0 on guest exit to prevent userspace taking advantage of the guest having set it non-zero (which would allow userspace to set its SMT priority to high). UAMOR is normally 0. We restore it to 0 on guest exit to prevent the AMR from being used as a covert channel between userspace processes, since the AMR is not context-switched at present. Fixes: b005255e12a3 ("KVM: PPC: Book3S HV: Context-switch new POWER8 SPRs", 2014-01-08) Cc: stable@vger.kernel.org # v3.14+ Signed-off-by: Paul Mackerras --- arch/powerpc/kvm/book3s_hv.c | 11 +++++++++-- arch/powerpc/kvm/book3s_hv_rmhandlers.S | 9 ++++++++- 2 files changed, 17 insertions(+), 3 deletions(-) (limited to 'arch') diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 400a5992b121..a963762a031f 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -2908,6 +2908,8 @@ static int kvmppc_vcpu_run_hv(struct kvm_run *run, struct kvm_vcpu *vcpu) int r; int srcu_idx; unsigned long ebb_regs[3] = {}; /* shut up GCC */ + unsigned long user_tar = 0; + unsigned int user_vrsave; if (!vcpu->arch.sane) { run->exit_reason = KVM_EXIT_INTERNAL_ERROR; @@ -2935,12 +2937,14 @@ static int kvmppc_vcpu_run_hv(struct kvm_run *run, struct kvm_vcpu *vcpu) flush_all_to_thread(current); - /* Save userspace EBB register values */ + /* Save userspace EBB and other register values */ if (cpu_has_feature(CPU_FTR_ARCH_207S)) { ebb_regs[0] = mfspr(SPRN_EBBHR); ebb_regs[1] = mfspr(SPRN_EBBRR); ebb_regs[2] = mfspr(SPRN_BESCR); + user_tar = mfspr(SPRN_TAR); } + user_vrsave = mfspr(SPRN_VRSAVE); vcpu->arch.wqp = &vcpu->arch.vcore->wq; vcpu->arch.pgdir = current->mm->pgd; @@ -2968,12 +2972,15 @@ static int kvmppc_vcpu_run_hv(struct kvm_run *run, struct kvm_vcpu *vcpu) } } while (is_kvmppc_resume_guest(r)); - /* Restore userspace EBB register values */ + /* Restore userspace EBB and other register values */ if (cpu_has_feature(CPU_FTR_ARCH_207S)) { mtspr(SPRN_EBBHR, ebb_regs[0]); mtspr(SPRN_EBBRR, ebb_regs[1]); mtspr(SPRN_BESCR, ebb_regs[2]); + mtspr(SPRN_TAR, user_tar); + mtspr(SPRN_FSCR, current->thread.fscr); } + mtspr(SPRN_VRSAVE, user_vrsave); out: vcpu->arch.state = KVMPPC_VCPU_NOTREADY; diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S index e390b383b4d6..4e4390564276 100644 --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S @@ -558,6 +558,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) #define STACK_SLOT_TID (112-16) #define STACK_SLOT_PSSCR (112-24) #define STACK_SLOT_PID (112-32) +#define STACK_SLOT_IAMR (112-40) .global kvmppc_hv_entry kvmppc_hv_entry: @@ -758,9 +759,11 @@ BEGIN_FTR_SECTION mfspr r5, SPRN_TIDR mfspr r6, SPRN_PSSCR mfspr r7, SPRN_PID + mfspr r8, SPRN_IAMR std r5, STACK_SLOT_TID(r1) std r6, STACK_SLOT_PSSCR(r1) std r7, STACK_SLOT_PID(r1) + std r8, STACK_SLOT_IAMR(r1) END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300) BEGIN_FTR_SECTION @@ -1515,11 +1518,12 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_ARCH_300) * set by the guest could disrupt the host. */ li r0, 0 - mtspr SPRN_IAMR, r0 mtspr SPRN_CIABR, r0 mtspr SPRN_DAWRX, r0 + mtspr SPRN_PSPB, r0 mtspr SPRN_WORT, r0 BEGIN_FTR_SECTION + mtspr SPRN_IAMR, r0 mtspr SPRN_TCSCR, r0 /* Set MMCRS to 1<<31 to freeze and disable the SPMC counters */ li r0, 1 @@ -1535,6 +1539,7 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300) std r6,VCPU_UAMOR(r9) li r6,0 mtspr SPRN_AMR,r6 + mtspr SPRN_UAMOR, r6 /* Switch DSCR back to host value */ mfspr r8, SPRN_DSCR @@ -1683,9 +1688,11 @@ BEGIN_FTR_SECTION ld r5, STACK_SLOT_TID(r1) ld r6, STACK_SLOT_PSSCR(r1) ld r7, STACK_SLOT_PID(r1) + ld r8, STACK_SLOT_IAMR(r1) mtspr SPRN_TIDR, r5 mtspr SPRN_PSSCR, r6 mtspr SPRN_PID, r7 + mtspr SPRN_IAMR, r8 END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300) BEGIN_FTR_SECTION PPC_INVALIDATE_ERAT -- cgit 1.4.1 From 46a704f8409f79fd66567ad3f8a7304830a84293 Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Thu, 15 Jun 2017 16:10:27 +1000 Subject: KVM: PPC: Book3S HV: Preserve userspace HTM state properly If userspace attempts to call the KVM_RUN ioctl when it has hardware transactional memory (HTM) enabled, the values that it has put in the HTM-related SPRs TFHAR, TFIAR and TEXASR will get overwritten by guest values. To fix this, we detect this condition and save those SPR values in the thread struct, and disable HTM for the task. If userspace goes to access those SPRs or the HTM facility in future, a TM-unavailable interrupt will occur and the handler will reload those SPRs and re-enable HTM. If userspace has started a transaction and suspended it, we would currently lose the transactional state in the guest entry path and would almost certainly get a "TM Bad Thing" interrupt, which would cause the host to crash. To avoid this, we detect this case and return from the KVM_RUN ioctl with an EINVAL error, with the KVM exit reason set to KVM_EXIT_FAIL_ENTRY. Fixes: b005255e12a3 ("KVM: PPC: Book3S HV: Context-switch new POWER8 SPRs", 2014-01-08) Cc: stable@vger.kernel.org # v3.14+ Signed-off-by: Paul Mackerras --- arch/powerpc/kvm/book3s_hv.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) (limited to 'arch') diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index a963762a031f..fd4d978d5257 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -2916,6 +2916,27 @@ static int kvmppc_vcpu_run_hv(struct kvm_run *run, struct kvm_vcpu *vcpu) return -EINVAL; } + /* + * Don't allow entry with a suspended transaction, because + * the guest entry/exit code will lose it. + * If the guest has TM enabled, save away their TM-related SPRs + * (they will get restored by the TM unavailable interrupt). + */ +#ifdef CONFIG_PPC_TRANSACTIONAL_MEM + if (cpu_has_feature(CPU_FTR_TM) && current->thread.regs && + (current->thread.regs->msr & MSR_TM)) { + if (MSR_TM_ACTIVE(current->thread.regs->msr)) { + run->exit_reason = KVM_EXIT_FAIL_ENTRY; + run->fail_entry.hardware_entry_failure_reason = 0; + return -EINVAL; + } + current->thread.tm_tfhar = mfspr(SPRN_TFHAR); + current->thread.tm_tfiar = mfspr(SPRN_TFIAR); + current->thread.tm_texasr = mfspr(SPRN_TEXASR); + current->thread.regs->msr &= ~MSR_TM; + } +#endif + kvmppc_core_prepare_to_enter(vcpu); /* No need to go into the guest when all we'll do is come back out */ -- cgit 1.4.1 From 7ceaa6dcd8c6f59588428cec37f3c8093dd1011f Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Fri, 16 Jun 2017 11:53:19 +1000 Subject: KVM: PPC: Book3S HV: Save/restore host values of debug registers At present, HV KVM on POWER8 and POWER9 machines loses any instruction or data breakpoint set in the host whenever a guest is run. Instruction breakpoints are currently only used by xmon, but ptrace and the perf_event subsystem can set data breakpoints as well as xmon. To fix this, we save the host values of the debug registers (CIABR, DAWR and DAWRX) before entering the guest and restore them on exit. To provide space to save them in the stack frame, we expand the stack frame allocated by kvmppc_hv_entry() from 112 to 144 bytes. Fixes: b005255e12a3 ("KVM: PPC: Book3S HV: Context-switch new POWER8 SPRs", 2014-01-08) Cc: stable@vger.kernel.org # v3.14+ Signed-off-by: Paul Mackerras --- arch/powerpc/kvm/book3s_hv_rmhandlers.S | 45 +++++++++++++++++++++++---------- 1 file changed, 32 insertions(+), 13 deletions(-) (limited to 'arch') diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S index 4e4390564276..4888dd494604 100644 --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S @@ -44,6 +44,17 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300) #define NAPPING_CEDE 1 #define NAPPING_NOVCPU 2 +/* Stack frame offsets for kvmppc_hv_entry */ +#define SFS 144 +#define STACK_SLOT_TRAP (SFS-4) +#define STACK_SLOT_TID (SFS-16) +#define STACK_SLOT_PSSCR (SFS-24) +#define STACK_SLOT_PID (SFS-32) +#define STACK_SLOT_IAMR (SFS-40) +#define STACK_SLOT_CIABR (SFS-48) +#define STACK_SLOT_DAWR (SFS-56) +#define STACK_SLOT_DAWRX (SFS-64) + /* * Call kvmppc_hv_entry in real mode. * Must be called with interrupts hard-disabled. @@ -328,10 +339,10 @@ kvm_novcpu_exit: bl kvmhv_accumulate_time #endif 13: mr r3, r12 - stw r12, 112-4(r1) + stw r12, STACK_SLOT_TRAP(r1) bl kvmhv_commence_exit nop - lwz r12, 112-4(r1) + lwz r12, STACK_SLOT_TRAP(r1) b kvmhv_switch_to_host /* @@ -554,12 +565,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) * * *****************************************************************************/ -/* Stack frame offsets */ -#define STACK_SLOT_TID (112-16) -#define STACK_SLOT_PSSCR (112-24) -#define STACK_SLOT_PID (112-32) -#define STACK_SLOT_IAMR (112-40) - .global kvmppc_hv_entry kvmppc_hv_entry: @@ -575,7 +580,7 @@ kvmppc_hv_entry: */ mflr r0 std r0, PPC_LR_STKOFF(r1) - stdu r1, -112(r1) + stdu r1, -SFS(r1) /* Save R1 in the PACA */ std r1, HSTATE_HOST_R1(r13) @@ -765,6 +770,14 @@ BEGIN_FTR_SECTION std r7, STACK_SLOT_PID(r1) std r8, STACK_SLOT_IAMR(r1) END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300) +BEGIN_FTR_SECTION + mfspr r5, SPRN_CIABR + mfspr r6, SPRN_DAWR + mfspr r7, SPRN_DAWRX + std r5, STACK_SLOT_CIABR(r1) + std r6, STACK_SLOT_DAWR(r1) + std r7, STACK_SLOT_DAWRX(r1) +END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) BEGIN_FTR_SECTION /* Set partition DABR */ @@ -1518,8 +1531,6 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_ARCH_300) * set by the guest could disrupt the host. */ li r0, 0 - mtspr SPRN_CIABR, r0 - mtspr SPRN_DAWRX, r0 mtspr SPRN_PSPB, r0 mtspr SPRN_WORT, r0 BEGIN_FTR_SECTION @@ -1684,6 +1695,14 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) ptesync /* Restore host values of some registers */ +BEGIN_FTR_SECTION + ld r5, STACK_SLOT_CIABR(r1) + ld r6, STACK_SLOT_DAWR(r1) + ld r7, STACK_SLOT_DAWRX(r1) + mtspr SPRN_CIABR, r5 + mtspr SPRN_DAWR, r6 + mtspr SPRN_DAWRX, r7 +END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) BEGIN_FTR_SECTION ld r5, STACK_SLOT_TID(r1) ld r6, STACK_SLOT_PSSCR(r1) @@ -1836,8 +1855,8 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_TYPE_RADIX) li r0, KVM_GUEST_MODE_NONE stb r0, HSTATE_IN_GUEST(r13) - ld r0, 112+PPC_LR_STKOFF(r1) - addi r1, r1, 112 + ld r0, SFS+PPC_LR_STKOFF(r1) + addi r1, r1, SFS mtlr r0 blr -- cgit 1.4.1 From 3d3efb68c19e539f0535c93a5258c1299270215f Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Tue, 6 Jun 2017 14:35:30 +1000 Subject: KVM: PPC: Book3S HV: Ignore timebase offset on POWER9 DD1 POWER9 DD1 has an erratum where writing to the TBU40 register, which is used to apply an offset to the timebase, can cause the timebase to lose counts. This results in the timebase on some CPUs getting out of sync with other CPUs, which then results in misbehaviour of the timekeeping code. To work around the problem, we make KVM ignore the timebase offset for all guests on POWER9 DD1 machines. This means that live migration cannot be supported on POWER9 DD1 machines. Cc: stable@vger.kernel.org # v4.10+ Signed-off-by: Paul Mackerras --- arch/powerpc/kvm/book3s_hv.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'arch') diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index fd4d978d5257..8d1a365b8edc 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -1486,6 +1486,14 @@ static int kvmppc_set_one_reg_hv(struct kvm_vcpu *vcpu, u64 id, r = set_vpa(vcpu, &vcpu->arch.dtl, addr, len); break; case KVM_REG_PPC_TB_OFFSET: + /* + * POWER9 DD1 has an erratum where writing TBU40 causes + * the timebase to lose ticks. So we don't let the + * timebase offset be changed on P9 DD1. (It is + * initialized to zero.) + */ + if (cpu_has_feature(CPU_FTR_POWER9_DD1)) + break; /* round up to multiple of 2^24 */ vcpu->arch.vcore->tb_offset = ALIGN(set_reg_val(id, *val), 1UL << 24); -- cgit 1.4.1