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From: Paolo Bonzini <pbonzini@redhat.com>
To: Xiaoyao Li <xiaoyao.li@intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Sean Christopherson <sean.j.christopherson@intel.com>
Cc: x86@kernel.org, "Kenneth R . Crudup" <kenny@panix.com>,
	Fenghua Yu <fenghua.yu@intel.com>, Nadav Amit <namit@vmware.com>,
	Thomas Hellstrom <thellstrom@vmware.com>,
	Tony Luck <tony.luck@intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Jessica Yu <jeyu@kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] x86/split_lock: Refactor and export handle_user_split_lock() for KVM
Date: Fri, 10 Apr 2020 12:21:36 +0200	[thread overview]
Message-ID: <283c549a-423f-a85e-c208-8a80d682ef77@redhat.com> (raw)
In-Reply-To: <716f5824-8d47-24cc-4935-c2dd32ed4629@intel.com>

On 10/04/20 06:39, Xiaoyao Li wrote:
> 
>   +static bool guest_handles_ac(struct kvm_vcpu *vcpu)
> +{
> +    /*
> +     * If guest has alignment checking enabled in CR0 and activated in
> +     * eflags, then the #AC originated from CPL3 and the guest is able
> +     * to handle it. It does not matter whether this is a regular or
> +     * a split lock operation induced #AC.
> +     */
> +    if (vmx_get_cpl(vcpu) == 3 && kvm_read_cr0_bits(vcpu, X86_CR0_AM) &&
> +        kvm_get_rflags(vcpu) & X86_EFLAGS_AC)
> +        return true;
> +
> +    /* Add guest SLD handling checks here once it's supported */
> +    return false;
> +}
> +
>   static int handle_exception_nmi(struct kvm_vcpu *vcpu)
>   {
>       struct vcpu_vmx *vmx = to_vmx(vcpu);
> @@ -4630,6 +4647,7 @@ static int handle_exception_nmi(struct k
>       u32 intr_info, ex_no, error_code;
>       unsigned long cr2, rip, dr6;
>       u32 vect_info;
> +    int err;
>         vect_info = vmx->idt_vectoring_info;
>       intr_info = vmx->exit_intr_info;
> @@ -4688,9 +4706,6 @@ static int handle_exception_nmi(struct k
>           return handle_rmode_exception(vcpu, ex_no, error_code);
>         switch (ex_no) {
> -    case AC_VECTOR:
> -        kvm_queue_exception_e(vcpu, AC_VECTOR, error_code);
> -        return 1;
>       case DB_VECTOR:
>           dr6 = vmcs_readl(EXIT_QUALIFICATION);
>           if (!(vcpu->guest_debug &
> @@ -4719,6 +4734,29 @@ static int handle_exception_nmi(struct k
>           kvm_run->debug.arch.pc = vmcs_readl(GUEST_CS_BASE) + rip;
>           kvm_run->debug.arch.exception = ex_no;
>           break;
> +    case AC_VECTOR:
> +        if (guest_handles_ac(vcpu)) {
> +            kvm_queue_exception_e(vcpu, AC_VECTOR, error_code);
> +            return 1;
> +        }
> +        /*
> +         * Handle #AC caused by split lock detection. If the host
> +         * mode is sld_warn, then it warns, marks current with
> +         * TIF_SLD and disables split lock detection. So the guest
> +         * can just continue.
> +         *
> +         * If the host mode is fatal, the handling code warned. Let
> +         * qemu kill itself.
> +         *
> +         * If the host mode is off, then this #AC is bonkers and
> +         * something is badly wrong. Let it fail as well.
> +         */
> +        err = handle_ac_split_lock(kvm_rip_read(vcpu));
> +        if (!err)
> +            return 1;
> +        /* Propagate the error type to user space */
> +        error_code = err == -EFAULT ? 0x100 : 0x200;
> +        fallthrough;


Acked-by: Paolo Bonzini <pbonzini@redhat.com>


  reply	other threads:[~2020-04-10 10:22 UTC|newest]

Thread overview: 78+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-02 12:32 [patch 0/2] x86: Prevent Split-Lock-Detection wreckage on VMX hypervisors Thomas Gleixner
2020-04-02 12:32 ` [patch 1/2] x86,module: Detect VMX modules and disable Split-Lock-Detect Thomas Gleixner
2020-04-02 15:23   ` [patch v2 " Peter Zijlstra
2020-04-02 16:20     ` Xiaoyao Li
2020-04-02 16:25       ` Peter Zijlstra
2020-04-02 16:39         ` Nadav Amit
2020-04-02 16:41         ` Xiaoyao Li
2020-04-02 17:34           ` Thomas Gleixner
2020-04-02 17:51             ` Sean Christopherson
2020-04-02 18:51               ` Peter Zijlstra
2020-04-02 20:23                 ` Sean Christopherson
2020-04-02 21:04                   ` Thomas Gleixner
2020-04-02 21:16                     ` Sean Christopherson
2020-04-03  8:09     ` David Laight
2020-04-03 14:33       ` Peter Zijlstra
2020-04-02 23:42   ` [patch " Rasmus Villemoes
2020-04-03 14:35     ` Jessica Yu
2020-04-03 15:21       ` Peter Zijlstra
2020-04-03 16:01         ` Sean Christopherson
2020-04-03 16:12           ` Peter Zijlstra
2020-04-03 16:16             ` David Laight
2020-04-03 16:39               ` Peter Zijlstra
2020-04-03 16:25             ` Sean Christopherson
2020-04-03 16:40               ` Peter Zijlstra
2020-04-03 16:48                 ` Nadav Amit
2020-04-03 17:21                   ` Sean Christopherson
2020-04-03 18:53         ` Thomas Gleixner
2020-04-03 20:58           ` Andy Lutomirski
2020-04-03 21:49             ` Thomas Gleixner
2020-04-03 11:29   ` kbuild test robot
2020-04-03 11:29     ` [patch 1/2] x86, module: " kbuild test robot
2020-04-03 14:43   ` [patch 1/2] x86,module: " kbuild test robot
2020-04-03 14:43     ` [patch 1/2] x86, module: " kbuild test robot
2020-04-03 16:36   ` [patch 1/2] x86,module: " Sean Christopherson
2020-04-03 16:41     ` Peter Zijlstra
2020-04-03 18:35       ` Jessica Yu
2020-04-06 12:23   ` Christoph Hellwig
2020-04-06 14:40     ` Peter Zijlstra
2020-04-06 15:18       ` Christoph Hellwig
2020-04-06 15:22         ` Peter Zijlstra
2020-04-06 18:27           ` Steven Rostedt
2020-04-02 12:33 ` [patch 2/2] x86/kvm/vmx: Prevent split lock detection induced #AC wreckage Thomas Gleixner
2020-04-02 15:30   ` Sean Christopherson
2020-04-02 15:44     ` Nadav Amit
2020-04-02 16:04       ` Sean Christopherson
2020-04-02 16:56     ` Thomas Gleixner
2020-04-02 15:55   ` [PATCH 0/3] x86: KVM: VMX: Add basic split-lock #AC handling Sean Christopherson
2020-04-02 15:55     ` [PATCH 1/3] KVM: x86: Emulate split-lock access as a write in emulator Sean Christopherson
2020-04-02 15:55     ` [PATCH 2/3] x86/split_lock: Refactor and export handle_user_split_lock() for KVM Sean Christopherson
2020-04-02 17:01       ` Thomas Gleixner
2020-04-02 17:19         ` Sean Christopherson
2020-04-02 19:06           ` Thomas Gleixner
2020-04-10  4:39             ` Xiaoyao Li
2020-04-10 10:21               ` Paolo Bonzini [this message]
2020-04-02 15:55     ` [PATCH 3/3] KVM: VMX: Extend VMX's #AC interceptor to handle split lock #AC in guest Sean Christopherson
2020-04-02 17:19       ` Thomas Gleixner
2020-04-02 17:40         ` Sean Christopherson
2020-04-02 20:07           ` Thomas Gleixner
2020-04-02 20:36             ` Andy Lutomirski
2020-04-02 20:48             ` Peter Zijlstra
2020-04-02 20:51             ` Sean Christopherson
2020-04-02 22:27               ` Thomas Gleixner
2020-04-02 22:40                 ` Nadav Amit
2020-04-02 23:03                   ` Thomas Gleixner
2020-04-02 23:08                   ` Steven Rostedt
2020-04-02 23:16                     ` Kenneth R. Crudup
2020-04-02 23:18                       ` Jim Mattson
2020-04-03 12:16                         ` Thomas Gleixner
2020-04-10 10:23     ` [PATCH 0/3] x86: KVM: VMX: Add basic split-lock #AC handling Paolo Bonzini
2020-04-10 11:14       ` Thomas Gleixner
2020-04-02 13:43 ` [patch 0/2] x86: Prevent Split-Lock-Detection wreckage on VMX hypervisors Kenneth R. Crudup
2020-04-02 14:32   ` Peter Zijlstra
2020-04-02 14:41     ` Kenneth R. Crudup
2020-04-02 14:46       ` Peter Zijlstra
2020-04-02 14:53         ` Kenneth R. Crudup
2020-04-02 14:37   ` Thomas Gleixner
2020-04-02 14:47     ` Nadav Amit
2020-04-02 15:11       ` Peter Zijlstra

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