* Re: [PATCH] kvm:x86:Fix incorrect error paths in the function process_smi
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@ 2015-09-18 14:52 ` Paolo Bonzini
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From: Paolo Bonzini @ 2015-09-18 14:52 UTC (permalink / raw)
To: Nicholas Krause, gleb; +Cc: kvm, x86, linux-kernel
On 18/09/2015 16:46, Nicholas Krause wrote:
> This fixes the incorrect assumation that the function
> kvm_vcpu_write_guest always runs successfully and
> therefore checks if it fails by returning a error code
> and if so return immediately to the caller of the function
> process_smi as we cannot this work's intended work after
> this failed call to kvm_vcpu_write_guest.
>
> Signed-off-by: Nicholas Krause <xerofoify@gmail.com>
> ---
> arch/x86/kvm/x86.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index a60bdbc..4743a4b 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -6088,7 +6088,8 @@ static void process_smi(struct kvm_vcpu *vcpu)
> else
> process_smi_save_state_32(vcpu, buf);
>
> - kvm_vcpu_write_guest(vcpu, vcpu->arch.smbase + 0xfe00, buf, sizeof(buf));
> + if (kvm_vcpu_write_guest(vcpu, vcpu->arch.smbase + 0xfe00, buf, sizeof(buf)))
> + return;
>
> if (kvm_x86_ops->get_nmi_mask(vcpu))
> vcpu->arch.hflags |= HF_SMM_INSIDE_NMI_MASK;
>
The SMI was requested by the guest. If the guest failed to set up SMM
correctly, it's the guest's problem. Aborting the SMI does not match
what a real processor does.
Thanks,
Paolo
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