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Wed, 25 Sep 2019 05:42:57 +0000 (GMT) Received: from b01ledav003.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 3D479B205F; Wed, 25 Sep 2019 05:42:55 +0000 (GMT) Received: from [9.124.31.203] (unknown [9.124.31.203]) by b01ledav003.gho.pok.ibm.com (Postfix) with ESMTP; Wed, 25 Sep 2019 05:42:54 +0000 (GMT) Subject: Re: [PATCH v14 2/7] ppc: spapr: Introduce FWNMI capability To: David Gibson References: <156879398718.18368.17640174821710157715.stgit@aravinda> <156879433743.18368.1281417894007921022.stgit@aravinda> <20190925011200.GF17405@umbus> From: Aravinda Prasad Message-ID: Date: Wed, 25 Sep 2019 11:12:54 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <20190925011200.GF17405@umbus> Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2019-09-25_04:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1908290000 definitions=main-1909250058 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [generic] [fuzzy] X-Received-From: 148.163.156.1 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: aik@ozlabs.ru, qemu-devel@nongnu.org, groug@kaod.org, paulus@ozlabs.org, qemu-ppc@nongnu.org, ganeshgr@linux.ibm.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wednesday 25 September 2019 06:42 AM, David Gibson wrote: > On Wed, Sep 18, 2019 at 01:42:17PM +0530, Aravinda Prasad wrote: >> Introduce the KVM capability KVM_CAP_PPC_FWNMI so that >> the KVM causes guest exit with NMI as exit reason >> when it encounters a machine check exception on the >> address belonging to a guest. Without this capability >> enabled, KVM redirects machine check exceptions to >> guest's 0x200 vector. >> >> This patch also introduces fwnmi-mce capability to >> deal with the case when a guest with the >> KVM_CAP_PPC_FWNMI capability enabled is attempted >> to migrate to a host that does not support this >> capability. >> >> Signed-off-by: Aravinda Prasad > > Mostly ok, but there's one ugly problem. > >> --- >> hw/ppc/spapr.c | 1 + >> hw/ppc/spapr_caps.c | 29 +++++++++++++++++++++++++++++ >> include/hw/ppc/spapr.h | 4 +++- >> target/ppc/kvm.c | 26 ++++++++++++++++++++++++++ >> target/ppc/kvm_ppc.h | 12 ++++++++++++ >> 5 files changed, 71 insertions(+), 1 deletion(-) >> >> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c >> index ea56499..8288e8b 100644 >> --- a/hw/ppc/spapr.c >> +++ b/hw/ppc/spapr.c >> @@ -4487,6 +4487,7 @@ static void spapr_machine_class_init(ObjectClass *oc, void *data) >> smc->default_caps.caps[SPAPR_CAP_NESTED_KVM_HV] = SPAPR_CAP_OFF; >> smc->default_caps.caps[SPAPR_CAP_LARGE_DECREMENTER] = SPAPR_CAP_ON; >> smc->default_caps.caps[SPAPR_CAP_CCF_ASSIST] = SPAPR_CAP_OFF; >> + smc->default_caps.caps[SPAPR_CAP_FWNMI_MCE] = SPAPR_CAP_OFF; >> spapr_caps_add_properties(smc, &error_abort); >> smc->irq = &spapr_irq_dual; >> smc->dr_phb_enabled = true; >> diff --git a/hw/ppc/spapr_caps.c b/hw/ppc/spapr_caps.c >> index 481dfd2..c11ff87 100644 >> --- a/hw/ppc/spapr_caps.c >> +++ b/hw/ppc/spapr_caps.c >> @@ -496,6 +496,25 @@ static void cap_ccf_assist_apply(SpaprMachineState *spapr, uint8_t val, >> } >> } >> >> +static void cap_fwnmi_mce_apply(SpaprMachineState *spapr, uint8_t val, >> + Error **errp) >> +{ >> + if (!val) { >> + return; /* Disabled by default */ >> + } >> + >> + if (tcg_enabled()) { >> + /* >> + * TCG support may not be correct in some conditions (e.g., in case >> + * of software injected faults like duplicate SLBs). >> + */ >> + warn_report("Firmware Assisted Non-Maskable Interrupts not supported in TCG"); >> + } else if (kvm_enabled() && !kvmppc_has_cap_ppc_fwnmi()) { >> + error_setg(errp, >> +"Firmware Assisted Non-Maskable Interrupts not supported by KVM, try cap-fwnmi-mce=off"); >> + } >> +} >> + >> SpaprCapabilityInfo capability_table[SPAPR_CAP_NUM] = { >> [SPAPR_CAP_HTM] = { >> .name = "htm", >> @@ -595,6 +614,15 @@ SpaprCapabilityInfo capability_table[SPAPR_CAP_NUM] = { >> .type = "bool", >> .apply = cap_ccf_assist_apply, >> }, >> + [SPAPR_CAP_FWNMI_MCE] = { >> + .name = "fwnmi-mce", >> + .description = "Handle fwnmi machine check exceptions", >> + .index = SPAPR_CAP_FWNMI_MCE, >> + .get = spapr_cap_get_bool, >> + .set = spapr_cap_set_bool, >> + .type = "bool", >> + .apply = cap_fwnmi_mce_apply, >> + }, >> }; >> >> static SpaprCapabilities default_caps_with_cpu(SpaprMachineState *spapr, >> @@ -734,6 +762,7 @@ SPAPR_CAP_MIG_STATE(hpt_maxpagesize, SPAPR_CAP_HPT_MAXPAGESIZE); >> SPAPR_CAP_MIG_STATE(nested_kvm_hv, SPAPR_CAP_NESTED_KVM_HV); >> SPAPR_CAP_MIG_STATE(large_decr, SPAPR_CAP_LARGE_DECREMENTER); >> SPAPR_CAP_MIG_STATE(ccf_assist, SPAPR_CAP_CCF_ASSIST); >> +SPAPR_CAP_MIG_STATE(fwnmi, SPAPR_CAP_FWNMI_MCE); >> >> void spapr_caps_init(SpaprMachineState *spapr) >> { >> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h >> index 03111fd..66049ac 100644 >> --- a/include/hw/ppc/spapr.h >> +++ b/include/hw/ppc/spapr.h >> @@ -79,8 +79,10 @@ typedef enum { >> #define SPAPR_CAP_LARGE_DECREMENTER 0x08 >> /* Count Cache Flush Assist HW Instruction */ >> #define SPAPR_CAP_CCF_ASSIST 0x09 >> +/* FWNMI machine check handling */ >> +#define SPAPR_CAP_FWNMI_MCE 0x0A >> /* Num Caps */ >> -#define SPAPR_CAP_NUM (SPAPR_CAP_CCF_ASSIST + 1) >> +#define SPAPR_CAP_NUM (SPAPR_CAP_FWNMI_MCE + 1) >> >> /* >> * Capability Values >> diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c >> index 8c5b1f2..8b1ab78 100644 >> --- a/target/ppc/kvm.c >> +++ b/target/ppc/kvm.c >> @@ -85,6 +85,7 @@ static int cap_ppc_safe_indirect_branch; >> static int cap_ppc_count_cache_flush_assist; >> static int cap_ppc_nested_kvm_hv; >> static int cap_large_decr; >> +static int cap_ppc_fwnmi; >> >> static uint32_t debug_inst_opcode; >> >> @@ -2055,6 +2056,26 @@ void kvmppc_set_mpic_proxy(PowerPCCPU *cpu, int mpic_proxy) >> } >> } >> >> +int kvmppc_set_fwnmi(void) >> +{ >> + PowerPCCPU *cpu = POWERPC_CPU(first_cpu); >> + CPUState *cs = CPU(cpu); >> + int ret; >> + >> + ret = kvm_vcpu_enable_cap(cs, KVM_CAP_PPC_FWNMI, 0); >> + if (ret) { >> + error_report("This KVM version does not support FWNMI"); >> + return ret; >> + } >> + >> + /* >> + * cap_ppc_fwnmi is set when FWNMI is available and enabled in KVM >> + * and not just when FWNMI is available in KVM >> + */ >> + cap_ppc_fwnmi = 1; > > Using these cap globals is only slighly ugly when they can be > initialized very early and thereafter remain constant. However, since > you're only setting this later (in fact *never* until several patches > down the series, since kvmppc_set_fwnmi() isn't called), this makes it > very ugly with this global set at an indeterminite time having effects > on things the relative order of which is not at all obvious. > > I think it would make much more sense to eliminate the cap_ppc_fwnmi > global, and instead attempt the enable_cap in cap_fwnmi_mce_apply, > failing the apply if the enable_cap fails. ok > >> + return ret; >> +} >> + >> int kvmppc_smt_threads(void) >> { >> return cap_ppc_smt ? cap_ppc_smt : 1; >> @@ -2355,6 +2376,11 @@ bool kvmppc_has_cap_mmu_hash_v3(void) >> return cap_mmu_hash_v3; >> } >> >> +bool kvmppc_has_cap_ppc_fwnmi(void) >> +{ >> + return cap_ppc_fwnmi; >> +} >> + >> static bool kvmppc_power8_host(void) >> { >> bool ret = false; >> diff --git a/target/ppc/kvm_ppc.h b/target/ppc/kvm_ppc.h >> index 98bd7d5..ce5c1f9 100644 >> --- a/target/ppc/kvm_ppc.h >> +++ b/target/ppc/kvm_ppc.h >> @@ -27,6 +27,8 @@ void kvmppc_enable_h_page_init(void); >> void kvmppc_set_papr(PowerPCCPU *cpu); >> int kvmppc_set_compat(PowerPCCPU *cpu, uint32_t compat_pvr); >> void kvmppc_set_mpic_proxy(PowerPCCPU *cpu, int mpic_proxy); >> +int kvmppc_set_fwnmi(void); >> +bool kvmppc_has_cap_ppc_fwnmi(void); >> int kvmppc_smt_threads(void); >> void kvmppc_hint_smt_possible(Error **errp); >> int kvmppc_set_smt_threads(int smt); >> @@ -159,6 +161,16 @@ static inline void kvmppc_set_mpic_proxy(PowerPCCPU *cpu, int mpic_proxy) >> { >> } >> >> +static inline int kvmppc_set_fwnmi(void) >> +{ >> + return -1; >> +} >> + >> +static inline bool kvmppc_has_cap_ppc_fwnmi(void) >> +{ >> + return false; >> +} >> + >> static inline int kvmppc_smt_threads(void) >> { >> return 1; >> > -- Regards, Aravinda