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[83.57.170.138]) by smtp.gmail.com with ESMTPSA id 14sm6236352wmk.19.2020.07.24.02.12.53 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 24 Jul 2020 02:12:53 -0700 (PDT) Subject: Re: [PATCH] pseries: fix kvmppc_set_fwnmi() To: Laurent Vivier , qemu-devel@nongnu.org References: <20200724083533.281700-1-lvivier@redhat.com> From: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= Autocrypt: addr=philmd@redhat.com; keydata= mQINBDXML8YBEADXCtUkDBKQvNsQA7sDpw6YLE/1tKHwm24A1au9Hfy/OFmkpzo+MD+dYc+7 bvnqWAeGweq2SDq8zbzFZ1gJBd6+e5v1a/UrTxvwBk51yEkadrpRbi+r2bDpTJwXc/uEtYAB GvsTZMtiQVA4kRID1KCdgLa3zztPLCj5H1VZhqZsiGvXa/nMIlhvacRXdbgllPPJ72cLUkXf z1Zu4AkEKpccZaJspmLWGSzGu6UTZ7UfVeR2Hcc2KI9oZB1qthmZ1+PZyGZ/Dy+z+zklC0xl XIpQPmnfy9+/1hj1LzJ+pe3HzEodtlVA+rdttSvA6nmHKIt8Ul6b/h1DFTmUT1lN1WbAGxmg CH1O26cz5nTrzdjoqC/b8PpZiT0kO5MKKgiu5S4PRIxW2+RA4H9nq7nztNZ1Y39bDpzwE5Sp bDHzd5owmLxMLZAINtCtQuRbSOcMjZlg4zohA9TQP9krGIk+qTR+H4CV22sWldSkVtsoTaA2 qNeSJhfHQY0TyQvFbqRsSNIe2gTDzzEQ8itsmdHHE/yzhcCVvlUzXhAT6pIN0OT+cdsTTfif MIcDboys92auTuJ7U+4jWF1+WUaJ8gDL69ThAsu7mGDBbm80P3vvUZ4fQM14NkxOnuGRrJxO qjWNJ2ZUxgyHAh5TCxMLKWZoL5hpnvx3dF3Ti9HW2dsUUWICSQARAQABtDJQaGlsaXBwZSBN YXRoaWV1LURhdWTDqSAoUGhpbCkgPHBoaWxtZEByZWRoYXQuY29tPokCVQQTAQgAPwIbDwYL CQgHAwIGFQgCCQoLBBYCAwECHgECF4AWIQSJweePYB7obIZ0lcuio/1u3q3A3gUCXsfWwAUJ KtymWgAKCRCio/1u3q3A3ircD/9Vjh3aFNJ3uF3hddeoFg1H038wZr/xi8/rX27M1Vj2j9VH 0B8Olp4KUQw/hyO6kUxqkoojmzRpmzvlpZ0cUiZJo2bQIWnvScyHxFCv33kHe+YEIqoJlaQc JfKYlbCoubz+02E2A6bFD9+BvCY0LBbEj5POwyKGiDMjHKCGuzSuDRbCn0Mz4kCa7nFMF5Jv piC+JemRdiBd6102ThqgIsyGEBXuf1sy0QIVyXgaqr9O2b/0VoXpQId7yY7OJuYYxs7kQoXI 6WzSMpmuXGkmfxOgbc/L6YbzB0JOriX0iRClxu4dEUg8Bs2pNnr6huY2Ft+qb41RzCJvvMyu gS32LfN0bTZ6Qm2A8ayMtUQgnwZDSO23OKgQWZVglGliY3ezHZ6lVwC24Vjkmq/2yBSLakZE 6DZUjZzCW1nvtRK05ebyK6tofRsx8xB8pL/kcBb9nCuh70aLR+5cmE41X4O+MVJbwfP5s/RW 9BFSL3qgXuXso/3XuWTQjJJGgKhB6xXjMmb1J4q/h5IuVV4juv1Fem9sfmyrh+Wi5V1IzKI7 RPJ3KVb937eBgSENk53P0gUorwzUcO+ASEo3Z1cBKkJSPigDbeEjVfXQMzNt0oDRzpQqH2vp apo2jHnidWt8BsckuWZpxcZ9+/9obQ55DyVQHGiTN39hkETy3Emdnz1JVHTU0Q== Message-ID: <375c9cb8-ec59-9d30-000d-b58d14be0aa6@redhat.com> Date: Fri, 24 Jul 2020 11:12:53 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <20200724083533.281700-1-lvivier@redhat.com> Content-Language: en-US X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=205.139.110.120; envelope-from=philmd@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/24 01:23:10 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -40 X-Spam_score: -4.1 X-Spam_bar: ---- X-Spam_report: (-4.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action 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: Paolo Bonzini , qemu-ppc@nongnu.org, npiggin@gmail.com, kvm@vger.kernel.org, David Gibson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 7/24/20 10:35 AM, Laurent Vivier wrote: > QEMU issues the ioctl(KVM_CAP_PPC_FWNMI) on the first vCPU. > > If the first vCPU is currently running, the vCPU mutex is held > and the ioctl() cannot be done and waits until the mutex is released. > This never happens and the VM is stuck. > > To avoid this deadlock, issue the ioctl on the same vCPU doing the > RTAS call. > > The problem can be reproduced by booting a guest with several vCPUs > (the probability to have the problem is (n - 1) / n, n = # of CPUs), > and then by triggering a kernel crash with "echo c >/proc/sysrq-trigger". > > On the reboot, the kernel hangs after: > > ... > [ 0.000000] ----------------------------------------------------- > [ 0.000000] ppc64_pft_size = 0x0 > [ 0.000000] phys_mem_size = 0x48000000 > [ 0.000000] dcache_bsize = 0x80 > [ 0.000000] icache_bsize = 0x80 > [ 0.000000] cpu_features = 0x0001c06f8f4f91a7 > [ 0.000000] possible = 0x0003fbffcf5fb1a7 > [ 0.000000] always = 0x00000003800081a1 > [ 0.000000] cpu_user_features = 0xdc0065c2 0xaee00000 > [ 0.000000] mmu_features = 0x3c006041 > [ 0.000000] firmware_features = 0x00000085455a445f > [ 0.000000] physical_start = 0x8000000 > [ 0.000000] ----------------------------------------------------- > [ 0.000000] numa: NODE_DATA [mem 0x47f33c80-0x47f3ffff] > > Fixes: ec010c00665b ("ppc/spapr: KVM FWNMI should not be enabled until guest requests it") > Cc: npiggin@gmail.com > Signed-off-by: Laurent Vivier Reviewed-by: Philippe Mathieu-Daudé > --- > hw/ppc/spapr_rtas.c | 2 +- > target/ppc/kvm.c | 3 +-- > target/ppc/kvm_ppc.h | 4 ++-- > 3 files changed, 4 insertions(+), 5 deletions(-) > > diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c > index bcac0d00e7b6..513c7a84351b 100644 > --- a/hw/ppc/spapr_rtas.c > +++ b/hw/ppc/spapr_rtas.c > @@ -438,7 +438,7 @@ static void rtas_ibm_nmi_register(PowerPCCPU *cpu, > } > > if (kvm_enabled()) { > - if (kvmppc_set_fwnmi() < 0) { > + if (kvmppc_set_fwnmi(cpu) < 0) { > rtas_st(rets, 0, RTAS_OUT_NOT_SUPPORTED); > return; > } > diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c > index 2692f76130aa..d85ba8ffe00b 100644 > --- a/target/ppc/kvm.c > +++ b/target/ppc/kvm.c > @@ -2071,9 +2071,8 @@ bool kvmppc_get_fwnmi(void) > return cap_fwnmi; > } > > -int kvmppc_set_fwnmi(void) > +int kvmppc_set_fwnmi(PowerPCCPU *cpu) > { > - PowerPCCPU *cpu = POWERPC_CPU(first_cpu); > CPUState *cs = CPU(cpu); > > return kvm_vcpu_enable_cap(cs, KVM_CAP_PPC_FWNMI, 0); > diff --git a/target/ppc/kvm_ppc.h b/target/ppc/kvm_ppc.h > index 701c0c262be2..72e05f1cd2fc 100644 > --- a/target/ppc/kvm_ppc.h > +++ b/target/ppc/kvm_ppc.h > @@ -28,7 +28,7 @@ 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); > bool kvmppc_get_fwnmi(void); > -int kvmppc_set_fwnmi(void); > +int kvmppc_set_fwnmi(PowerPCCPU *cpu); > int kvmppc_smt_threads(void); > void kvmppc_error_append_smt_possible_hint(Error *const *errp); > int kvmppc_set_smt_threads(int smt); > @@ -169,7 +169,7 @@ static inline bool kvmppc_get_fwnmi(void) > return false; > } > > -static inline int kvmppc_set_fwnmi(void) > +static inline int kvmppc_set_fwnmi(PowerPCCPU *cpu) > { > return -1; > } >