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@xxxxxxxxxx>
