APPLIED: [PATCH 2/2][Bionic] KVM: x86: SVM: Set EMULTYPE_NO_REEXECUTE for RSM emulation

[Khaled Elmously]

On 2019-08-29 14:06:58 , Rafael David Tinoco wrote:
> From: Sean Christopherson <sean.j.christopherson at intel.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/1834522
> 
> Re-execution after an emulation decode failure is only intended to
> handle a case where two or vCPUs race to write a shadowed page, i.e.
> we should never re-execute an instruction as part of RSM emulation.
> 
> Add a new helper, kvm_emulate_instruction_from_buffer(), to support
> emulating from a pre-defined buffer.  This eliminates the last direct
> call to x86_emulate_instruction() outside of kvm_mmu_page_fault(),
> which means x86_emulate_instruction() can be unexported in a future
> patch.
> 
> Fixes: 7607b7174405 ("KVM: SVM: install RSM intercept")
> Cc: Brijesh Singh <brijesh.singh at amd.com>
> Signed-off-by: Sean Christopherson <sean.j.christopherson at intel.com>
> Cc: stable at vger.kernel.org
> Signed-off-by: Radim Krčmář <rkrcmar at redhat.com>
> (cherry-picked from 35be0aded76b54a24dc8aa678a71bca22273e8d8)
> Signed-off-by: Rafael David Tinoco <rafaeldtinoco at ubuntu.com>
> 
> ---
>  arch/x86/include/asm/kvm_host.h | 7 +++++++
>  arch/x86/kvm/svm.c              | 4 ++--
>  2 files changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index c2bb7da8e5b4..836426e6fd9b 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1189,6 +1189,13 @@ static inline int emulate_instruction(struct kvm_vcpu *vcpu,
>  			emulation_type | EMULTYPE_NO_REEXECUTE, NULL, 0);
>  }
>  
> +static inline int kvm_emulate_instruction_from_buffer(struct kvm_vcpu *vcpu,
> +						      void *insn, int insn_len)
> +{
> +	return x86_emulate_instruction(vcpu, 0, EMULTYPE_NO_REEXECUTE,
> +				       insn, insn_len);
> +}
> +
>  void kvm_enable_efer_bits(u64);
>  bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer);
>  int kvm_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr);
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 538ca5446cfd..235e5181e1a0 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -3446,8 +3446,8 @@ static int emulate_on_interception(struct vcpu_svm *svm)
>  
>  static int rsm_interception(struct vcpu_svm *svm)
>  {
> -	return x86_emulate_instruction(&svm->vcpu, 0, 0,
> -				       rsm_ins_bytes, 2) == EMULATE_DONE;
> +	return kvm_emulate_instruction_from_buffer(&svm->vcpu,
> +					rsm_ins_bytes, 2) == EMULATE_DONE;
>  }
>  
>  static int rdpmc_interception(struct vcpu_svm *svm)
> -- 
> 2.17.1
> 
> 
> -- 
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