From: "Philippe Mathieu-Daudé" <philmd@linaro.org>
To: Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Marc Zyngier <maz@kernel.org>,
Huacai Chen <chenhuacai@kernel.org>,
Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>,
Anup Patel <anup@brainfault.org>,
Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Janosch Frank <frankja@linux.ibm.com>,
Claudio Imbrenda <imbrenda@linux.ibm.com>,
Matthew Rosato <mjrosato@linux.ibm.com>,
Eric Farman <farman@linux.ibm.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
David Woodhouse <dwmw2@infradead.org>,
Paul Durrant <paul@xen.org>
Cc: kvm@vger.kernel.org, David Hildenbrand <david@redhat.com>,
Atish Patra <atishp@atishpatra.org>,
linux-kernel@vger.kernel.org, Kai Huang <kai.huang@intel.com>,
linux-riscv@lists.infradead.org, kvmarm@lists.cs.columbia.edu,
linux-s390@vger.kernel.org, Chao Gao <chao.gao@intel.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Yuan Yao <yuan.yao@intel.com>,
kvmarm@lists.linux.dev, Thomas Gleixner <tglx@linutronix.de>,
Alexandru Elisei <alexandru.elisei@arm.com>,
linux-arm-kernel@lists.infradead.org,
Isaku Yamahata <isaku.yamahata@intel.com>,
Fabiano Rosas <farosas@linux.ibm.com>,
Cornelia Huck <cohuck@redhat.com>,
linux-mips@vger.kernel.org, Oliver Upton <oliver.upton@linux.dev>,
James Morse <james.morse@arm.com>,
kvm-riscv@lists.infradead.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v2 21/50] KVM: MIPS: Hardcode callbacks to hardware virtualization extensions
Date: Thu, 1 Dec 2022 23:00:13 +0100 [thread overview]
Message-ID: <beb697c2-dfad-780e-4638-76b229f28731@linaro.org> (raw)
In-Reply-To: <20221130230934.1014142-22-seanjc@google.com>
On 1/12/22 00:09, Sean Christopherson wrote:
> Now that KVM no longer supports trap-and-emulate (see commit 45c7e8af4a5e
> "MIPS: Remove KVM_TE support"), hardcode the MIPS callbacks to the
> virtualization callbacks.
>
> Harcoding the callbacks eliminates the technically-unnecessary check on
> non-NULL kvm_mips_callbacks in kvm_arch_init(). MIPS has never supported
> multiple in-tree modules, i.e. barring an out-of-tree module, where
> copying and renaming kvm.ko counts as "out-of-tree", KVM could never
> encounter a non-NULL set of callbacks during module init.
>
> The callback check is also subtly broken, as it is not thread safe,
> i.e. if there were multiple modules, loading both concurrently would
> create a race between checking and setting kvm_mips_callbacks.
>
> Given that out-of-tree shenanigans are not the kernel's responsibility,
> hardcode the callbacks to simplify the code.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
> arch/mips/include/asm/kvm_host.h | 2 +-
> arch/mips/kvm/Makefile | 2 +-
> arch/mips/kvm/callback.c | 14 --------------
> arch/mips/kvm/mips.c | 9 ++-------
> arch/mips/kvm/vz.c | 7 ++++---
> 5 files changed, 8 insertions(+), 26 deletions(-)
> delete mode 100644 arch/mips/kvm/callback.c
>
> diff --git a/arch/mips/include/asm/kvm_host.h b/arch/mips/include/asm/kvm_host.h
> index 28f0ba97db71..2803c9c21ef9 100644
> --- a/arch/mips/include/asm/kvm_host.h
> +++ b/arch/mips/include/asm/kvm_host.h
> @@ -758,7 +758,7 @@ struct kvm_mips_callbacks {
> void (*vcpu_reenter)(struct kvm_vcpu *vcpu);
> };
> extern struct kvm_mips_callbacks *kvm_mips_callbacks;
IIUC we could even constify this pointer.
Anyway,
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
> index af29490d9740..f0a6c245d1ff 100644
> --- a/arch/mips/kvm/mips.c
> +++ b/arch/mips/kvm/mips.c
> @@ -1012,17 +1012,12 @@ long kvm_arch_vm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
>
> int kvm_arch_init(void *opaque)
> {
> - if (kvm_mips_callbacks) {
> - kvm_err("kvm: module already exists\n");
> - return -EEXIST;
> - }
> -
> - return kvm_mips_emulation_init(&kvm_mips_callbacks);
> + return kvm_mips_emulation_init();
> }
>
> void kvm_arch_exit(void)
> {
> - kvm_mips_callbacks = NULL;
> +
> }
>
> int kvm_arch_vcpu_ioctl_get_sregs(struct kvm_vcpu *vcpu,
> diff --git a/arch/mips/kvm/vz.c b/arch/mips/kvm/vz.c
> index c706f5890a05..dafab003ea0d 100644
> --- a/arch/mips/kvm/vz.c
> +++ b/arch/mips/kvm/vz.c
> @@ -3304,7 +3304,10 @@ static struct kvm_mips_callbacks kvm_vz_callbacks = {
> .vcpu_reenter = kvm_vz_vcpu_reenter,
> };
>
> -int kvm_mips_emulation_init(struct kvm_mips_callbacks **install_callbacks)
> +/* FIXME: Get rid of the callbacks now that trap-and-emulate is gone. */
> +struct kvm_mips_callbacks *kvm_mips_callbacks = &kvm_vz_callbacks;
next prev parent reply other threads:[~2022-12-01 22:01 UTC|newest]
Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-30 23:08 [PATCH v2 00/50] KVM: Rework kvm_init() and hardware enabling Sean Christopherson
2022-11-30 23:08 ` [PATCH v2 01/50] KVM: Register /dev/kvm as the _very_ last thing during initialization Sean Christopherson
2022-11-30 23:08 ` [PATCH v2 02/50] KVM: Initialize IRQ FD after arch hardware setup Sean Christopherson
2022-11-30 23:08 ` [PATCH v2 03/50] KVM: Allocate cpus_hardware_enabled " Sean Christopherson
2022-11-30 23:08 ` [PATCH v2 04/50] KVM: Teardown VFIO ops earlier in kvm_exit() Sean Christopherson
2022-11-30 23:08 ` [PATCH v2 05/50] KVM: s390: Unwind kvm_arch_init() piece-by-piece() if a step fails Sean Christopherson
2022-11-30 23:08 ` [PATCH v2 06/50] KVM: s390: Move hardware setup/unsetup to init/exit Sean Christopherson
2022-11-30 23:08 ` [PATCH v2 07/50] KVM: x86: Do timer initialization after XCR0 configuration Sean Christopherson
2022-11-30 23:08 ` [PATCH v2 08/50] KVM: x86: Move hardware setup/unsetup to init/exit Sean Christopherson
2022-11-30 23:08 ` [PATCH v2 09/50] KVM: Drop arch hardware (un)setup hooks Sean Christopherson
2022-11-30 23:08 ` [PATCH v2 10/50] KVM: VMX: Reset eVMCS controls in VP assist page during hardware disabling Sean Christopherson
2022-12-01 15:42 ` Vitaly Kuznetsov
2022-11-30 23:08 ` [PATCH v2 11/50] KVM: VMX: Don't bother disabling eVMCS static key on module exit Sean Christopherson
2022-11-30 23:08 ` [PATCH v2 12/50] KVM: VMX: Move Hyper-V eVMCS initialization to helper Sean Christopherson
2022-12-01 15:22 ` Vitaly Kuznetsov
2022-11-30 23:08 ` [PATCH v2 13/50] KVM: x86: Move guts of kvm_arch_init() to standalone helper Sean Christopherson
2022-11-30 23:08 ` [PATCH v2 14/50] KVM: VMX: Do _all_ initialization before exposing /dev/kvm to userspace Sean Christopherson
2022-11-30 23:08 ` [PATCH v2 15/50] KVM: x86: Serialize vendor module initialization (hardware setup) Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 16/50] KVM: arm64: Simplify the CPUHP logic Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 17/50] KVM: arm64: Free hypervisor allocations if vector slot init fails Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 18/50] KVM: arm64: Unregister perf callbacks if hypervisor finalization fails Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 19/50] KVM: arm64: Do arm/arch initialization without bouncing through kvm_init() Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 20/50] KVM: arm64: Mark kvm_arm_init() and its unique descendants as __init Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 21/50] KVM: MIPS: Hardcode callbacks to hardware virtualization extensions Sean Christopherson
2022-12-01 22:00 ` Philippe Mathieu-Daudé [this message]
2022-12-01 22:49 ` Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 22/50] KVM: MIPS: Setup VZ emulation? directly from kvm_mips_init() Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 23/50] KVM: MIPS: Register die notifier prior to kvm_init() Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 24/50] KVM: RISC-V: Do arch init directly in riscv_kvm_init() Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 25/50] KVM: RISC-V: Tag init functions and data with __init, __ro_after_init Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 26/50] KVM: PPC: Move processor compatibility check to module init Sean Christopherson
2022-12-01 5:21 ` Michael Ellerman
2022-12-01 16:38 ` Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 27/50] KVM: s390: Do s390 specific init without bouncing through kvm_init() Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 28/50] KVM: s390: Mark __kvm_s390_init() and its descendants as __init Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 29/50] KVM: Drop kvm_arch_{init,exit}() hooks Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 30/50] KVM: VMX: Make VMCS configuration/capabilities structs read-only after init Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 31/50] KVM: x86: Do CPU compatibility checks in x86 code Sean Christopherson
2022-12-02 12:16 ` Huang, Kai
2022-12-05 20:52 ` Isaku Yamahata
2022-12-05 21:12 ` Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 32/50] KVM: Drop kvm_arch_check_processor_compat() hook Sean Christopherson
2022-12-02 12:18 ` Huang, Kai
2022-11-30 23:09 ` [PATCH v2 33/50] KVM: x86: Use KBUILD_MODNAME to specify vendor module name Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 34/50] KVM: x86: Unify pr_fmt to use module name for all KVM modules Sean Christopherson
2022-12-01 10:43 ` Paul Durrant
2022-11-30 23:09 ` [PATCH v2 35/50] KVM: VMX: Use current CPU's info to perform "disabled by BIOS?" checks Sean Christopherson
2022-12-02 12:18 ` Huang, Kai
2022-11-30 23:09 ` [PATCH v2 36/50] KVM: x86: Do VMX/SVM support checks directly in vendor code Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 37/50] KVM: VMX: Shuffle support checks and hardware enabling code around Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 38/50] KVM: SVM: Check for SVM support in CPU compatibility checks Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 39/50] KVM: x86: Move CPU compat checks hook to kvm_x86_ops (from kvm_x86_init_ops) Sean Christopherson
2022-12-02 13:01 ` Huang, Kai
2022-12-05 21:04 ` Isaku Yamahata
2022-11-30 23:09 ` [PATCH v2 40/50] KVM: x86: Do compatibility checks when onlining CPU Sean Christopherson
2022-12-02 13:03 ` Huang, Kai
2022-12-02 13:36 ` Huang, Kai
2022-12-02 16:04 ` Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 41/50] KVM: Rename and move CPUHP_AP_KVM_STARTING to ONLINE section Sean Christopherson
2022-12-02 13:06 ` Huang, Kai
2022-12-02 16:08 ` Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 42/50] KVM: Disable CPU hotplug during hardware enabling/disabling Sean Christopherson
2022-12-02 12:59 ` Huang, Kai
2022-12-02 16:31 ` Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 43/50] KVM: Ensure CPU is stable during low level hardware enable/disable Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 44/50] KVM: Drop kvm_count_lock and instead protect kvm_usage_count with kvm_lock Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 45/50] KVM: Remove on_each_cpu(hardware_disable_nolock) in kvm_exit() Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 46/50] KVM: Use a per-CPU variable to track which CPUs have enabled virtualization Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 47/50] KVM: Make hardware_enable_failed a local variable in the "enable all" path Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 48/50] KVM: Register syscore (suspend/resume) ops early in kvm_init() Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 49/50] KVM: Opt out of generic hardware enabling on s390 and PPC Sean Christopherson
2022-11-30 23:09 ` [PATCH v2 50/50] KVM: Clean up error labels in kvm_init() Sean Christopherson
2022-12-02 8:02 ` [PATCH v2 00/50] KVM: Rework kvm_init() and hardware enabling Chao Gao
2022-12-27 13:02 ` Paolo Bonzini
2022-12-28 11:22 ` Marc Zyngier
2022-12-28 11:58 ` Paolo Bonzini
2022-12-29 20:52 ` Paolo Bonzini
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