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Fri, 15 Mar 2024 10:45:06 -0700 (PDT) Date: Fri, 15 Mar 2024 10:45:04 -0700 In-Reply-To: <88920c598dcb55c15219642f27d0781af6d0c044.1708933498.git.isaku.yamahata@intel.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <88920c598dcb55c15219642f27d0781af6d0c044.1708933498.git.isaku.yamahata@intel.com> Message-ID: Subject: Re: [PATCH v19 098/130] KVM: TDX: Add a place holder to handle TDX VM exit From: Sean Christopherson To: isaku.yamahata@intel.com Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, isaku.yamahata@gmail.com, Paolo Bonzini , erdemaktas@google.com, Sagi Shahar , Kai Huang , chen.bo@intel.com, hang.yuan@intel.com, tina.zhang@intel.com Content-Type: text/plain; charset="us-ascii" On Mon, Feb 26, 2024, isaku.yamahata@intel.com wrote: > +int tdx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t fastpath) > +{ > + union tdx_exit_reason exit_reason = to_tdx(vcpu)->exit_reason; > + > + /* See the comment of tdh_sept_seamcall(). */ > + if (unlikely(exit_reason.full == (TDX_OPERAND_BUSY | TDX_OPERAND_ID_SEPT))) > + return 1; > + > + /* > + * TDH.VP.ENTRY checks TD EPOCH which contend with TDH.MEM.TRACK and > + * vcpu TDH.VP.ENTER. > + */ > + if (unlikely(exit_reason.full == (TDX_OPERAND_BUSY | TDX_OPERAND_ID_TD_EPOCH))) > + return 1; > + > + if (unlikely(exit_reason.full == TDX_SEAMCALL_UD)) { > + kvm_spurious_fault(); > + /* > + * In the case of reboot or kexec, loop with TDH.VP.ENTER and > + * TDX_SEAMCALL_UD to avoid unnecessarily activity. > + */ > + return 1; No. This is unnecessarily risky. KVM_BUG_ON() and exit to userspace. The response to "SEAMCALL faulted" should never be, "well, let's try again!". Also, what about #GP on SEAMCALL? In general, the error handling here seems lacking.