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Message-ID: <20221205205246.GA3630770@ls.amr.corp.intel.com>
Date: Mon, 5 Dec 2022 12:52:46 -0800
From: Isaku Yamahata <isaku.yamahata@...il.com>
To: Sean Christopherson <seanjc@...gle.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>, Marc Zyngier <maz@...nel.org>,
Huacai Chen <chenhuacai@...nel.org>,
Aleksandar Markovic <aleksandar.qemu.devel@...il.com>,
Anup Patel <anup@...infault.org>,
Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
Christian Borntraeger <borntraeger@...ux.ibm.com>,
Janosch Frank <frankja@...ux.ibm.com>,
Claudio Imbrenda <imbrenda@...ux.ibm.com>,
Matthew Rosato <mjrosato@...ux.ibm.com>,
Eric Farman <farman@...ux.ibm.com>,
Vitaly Kuznetsov <vkuznets@...hat.com>,
David Woodhouse <dwmw2@...radead.org>,
Paul Durrant <paul@....org>, James Morse <james.morse@....com>,
Alexandru Elisei <alexandru.elisei@....com>,
Suzuki K Poulose <suzuki.poulose@....com>,
Oliver Upton <oliver.upton@...ux.dev>,
Atish Patra <atishp@...shpatra.org>,
David Hildenbrand <david@...hat.com>, kvm@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev,
kvmarm@...ts.cs.columbia.edu, linux-mips@...r.kernel.org,
linuxppc-dev@...ts.ozlabs.org, kvm-riscv@...ts.infradead.org,
linux-riscv@...ts.infradead.org, linux-s390@...r.kernel.org,
linux-kernel@...r.kernel.org, Yuan Yao <yuan.yao@...el.com>,
Cornelia Huck <cohuck@...hat.com>,
Isaku Yamahata <isaku.yamahata@...el.com>,
Philippe Mathieu-Daudé <philmd@...aro.org>,
Fabiano Rosas <farosas@...ux.ibm.com>,
Michael Ellerman <mpe@...erman.id.au>,
Kai Huang <kai.huang@...el.com>, Chao Gao <chao.gao@...el.com>,
Thomas Gleixner <tglx@...utronix.de>, isaku.yamahata@...il.com
Subject: Re: [PATCH v2 31/50] KVM: x86: Do CPU compatibility checks in x86
code
On Wed, Nov 30, 2022 at 11:09:15PM +0000,
Sean Christopherson <seanjc@...gle.com> wrote:
> Move the CPU compatibility checks to pure x86 code, i.e. drop x86's use
> of the common kvm_x86_check_cpu_compat() arch hook. x86 is the only
> architecture that "needs" to do per-CPU compatibility checks, moving
> the logic to x86 will allow dropping the common code, and will also
> give x86 more control over when/how the compatibility checks are
> performed, e.g. TDX will need to enable hardware (do VMXON) in order to
> perform compatibility checks.
>
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> ---
> arch/x86/kvm/svm/svm.c | 2 +-
> arch/x86/kvm/vmx/vmx.c | 2 +-
> arch/x86/kvm/x86.c | 49 ++++++++++++++++++++++++++++++++----------
> 3 files changed, 40 insertions(+), 13 deletions(-)
>
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index 19e81a99c58f..d7ea1c1175c2 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -5103,7 +5103,7 @@ static int __init svm_init(void)
> * Common KVM initialization _must_ come last, after this, /dev/kvm is
> * exposed to userspace!
> */
> - r = kvm_init(&svm_init_ops, sizeof(struct vcpu_svm),
> + r = kvm_init(NULL, sizeof(struct vcpu_svm),
> __alignof__(struct vcpu_svm), THIS_MODULE);
> if (r)
> goto err_kvm_init;
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 654d81f781da..8deb1bd60c10 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -8592,7 +8592,7 @@ static int __init vmx_init(void)
> * Common KVM initialization _must_ come last, after this, /dev/kvm is
> * exposed to userspace!
> */
> - r = kvm_init(&vmx_init_ops, sizeof(struct vcpu_vmx),
> + r = kvm_init(NULL, sizeof(struct vcpu_vmx),
> __alignof__(struct vcpu_vmx), THIS_MODULE);
> if (r)
> goto err_kvm_init;
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 66f16458aa97..3571bc968cf8 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -9277,10 +9277,36 @@ static inline void kvm_ops_update(struct kvm_x86_init_ops *ops)
> kvm_pmu_ops_update(ops->pmu_ops);
> }
>
> +struct kvm_cpu_compat_check {
> + struct kvm_x86_init_ops *ops;
> + int *ret;
minor nitpick: just int ret. I don't see the necessity of the pointer.
Anyway overall it looks good to me.
Reviewed-by: Isaku Yamahata <isaku.yamahata@...el.com>
> +};
> +
> +static int kvm_x86_check_processor_compatibility(struct kvm_x86_init_ops *ops)
> +{
> + struct cpuinfo_x86 *c = &cpu_data(smp_processor_id());
> +
> + WARN_ON(!irqs_disabled());
> +
> + if (__cr4_reserved_bits(cpu_has, c) !=
> + __cr4_reserved_bits(cpu_has, &boot_cpu_data))
> + return -EIO;
> +
> + return ops->check_processor_compatibility();
> +}
> +
> +static void kvm_x86_check_cpu_compat(void *data)
> +{
> + struct kvm_cpu_compat_check *c = data;
> +
> + *c->ret = kvm_x86_check_processor_compatibility(c->ops);
> +}
> +
> static int __kvm_x86_vendor_init(struct kvm_x86_init_ops *ops)
> {
> + struct kvm_cpu_compat_check c;
> u64 host_pat;
> - int r;
> + int r, cpu;
>
> if (kvm_x86_ops.hardware_enable) {
> pr_err("kvm: already loaded vendor module '%s'\n", kvm_x86_ops.name);
> @@ -9360,6 +9386,14 @@ static int __kvm_x86_vendor_init(struct kvm_x86_init_ops *ops)
> if (r != 0)
> goto out_mmu_exit;
>
> + c.ret = &r;
> + c.ops = ops;
> + for_each_online_cpu(cpu) {
> + smp_call_function_single(cpu, kvm_x86_check_cpu_compat, &c, 1);
> + if (r < 0)
Here it can be "c.ret < 0".
> + goto out_hardware_unsetup;
> + }
> +
> /*
> * Point of no return! DO NOT add error paths below this point unless
> * absolutely necessary, as most operations from this point forward
> @@ -9402,6 +9436,8 @@ static int __kvm_x86_vendor_init(struct kvm_x86_init_ops *ops)
> kvm_init_msr_list();
> return 0;
>
> +out_hardware_unsetup:
> + ops->runtime_ops->hardware_unsetup();
> out_mmu_exit:
> kvm_mmu_vendor_module_exit();
> out_free_percpu:
> @@ -12037,16 +12073,7 @@ void kvm_arch_hardware_disable(void)
>
> int kvm_arch_check_processor_compat(void *opaque)
> {
> - struct cpuinfo_x86 *c = &cpu_data(smp_processor_id());
> - struct kvm_x86_init_ops *ops = opaque;
> -
> - WARN_ON(!irqs_disabled());
> -
> - if (__cr4_reserved_bits(cpu_has, c) !=
> - __cr4_reserved_bits(cpu_has, &boot_cpu_data))
> - return -EIO;
> -
> - return ops->check_processor_compatibility();
> + return 0;
> }
>
> bool kvm_vcpu_is_reset_bsp(struct kvm_vcpu *vcpu)
> --
> 2.38.1.584.g0f3c55d4c2-goog
>
--
Isaku Yamahata <isaku.yamahata@...il.com>
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