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h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=T1OP+GAJvhLMjzOh/5TIEdqdp9NsnlXhvwuvg2gKsckc0/pkc8oKjxyhMdT6Xao0Q picKvgtfPLFGRss5J40j6thW5IDrO7LywYungopY0Kj0993ISgJp0WKwFhvfw8NTCn cMpUyStMlCondNxEFuaDoZZ/A81TV7rHtYq9afjZuUT+Yv06gtsDWTY1nYdoCKpEtP gGnLbgzcRuPEXqdCUkrk/MJ3jIt2AypPkGrwmwh6yyO67NJN9tPlMHAFPy8X8+g6C9 C5KWYJXgx97TChOaVIftR5ZO6Bv6GoJF4SeXRskSDOUvXDqrcHhzMCKqChAYDbVxn4 k8Pecq0DRX9NQ== Message-ID: <5ded5ea5-6a31-47ef-ae12-f32615ada248@zytor.com> Date: Fri, 25 Oct 2024 01:04:16 -0700 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 16/27] KVM: VMX: Virtualize FRED nested exception tracking To: Chao Gao Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, seanjc@google.com, pbonzini@redhat.com, corbet@lwn.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, luto@kernel.org, peterz@infradead.org, andrew.cooper3@citrix.com References: <20241001050110.3643764-1-xin@zytor.com> <20241001050110.3643764-17-xin@zytor.com> Content-Language: en-US From: Xin Li Autocrypt: addr=xin@zytor.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 10/23/2024 11:24 PM, Chao Gao wrote: >> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h >> index b9b82aaea9a3..3830084b569b 100644 >> --- a/arch/x86/include/asm/kvm_host.h >> +++ b/arch/x86/include/asm/kvm_host.h >> @@ -736,6 +736,7 @@ struct kvm_queued_exception { >> u32 error_code; >> unsigned long payload; >> bool has_payload; >> + bool nested; >> u64 event_data; > > how "nested" is migrated in live migration? Damn, I forgot it! Looks we need to add it to kvm_vcpu_ioctl_x86_{get,set}_vcpu_events(), but the real question is how to add it to struct kvm_vcpu_events. > >> }; > > [..] > >> >> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c >> index d81144bd648f..03f42b218554 100644 >> --- a/arch/x86/kvm/vmx/vmx.c >> +++ b/arch/x86/kvm/vmx/vmx.c >> @@ -1910,8 +1910,11 @@ void vmx_inject_exception(struct kvm_vcpu *vcpu) >> vmcs_write32(VM_ENTRY_INSTRUCTION_LEN, >> vmx->vcpu.arch.event_exit_inst_len); >> intr_info |= INTR_TYPE_SOFT_EXCEPTION; >> - } else >> + } else { >> intr_info |= INTR_TYPE_HARD_EXCEPTION; >> + if (ex->nested) >> + intr_info |= INTR_INFO_NESTED_EXCEPTION_MASK; > > how about moving the is_fred_enable() check from kvm_multiple_exception() to here? i.e., > > if (ex->nested && is_fred_enabled(vcpu)) > intr_info |= INTR_INFO_NESTED_EXCEPTION_MASK; > > It is slightly clearer because FRED details don't bleed into kvm_multiple_exception(). But FRED is all about events, including exception/interrupt/trap/... logically VMX nested exception only works when FRED is enabled, see how it is set at 2 places in kvm_multiple_exception(). > >> + } >> >> vmcs_write32(VM_ENTRY_INTR_INFO_FIELD, intr_info); >> >> @@ -7290,6 +7293,7 @@ static void __vmx_complete_interrupts(struct kvm_vcpu *vcpu, >> kvm_requeue_exception(vcpu, vector, >> idt_vectoring_info & VECTORING_INFO_DELIVER_CODE_MASK, >> error_code, >> + idt_vectoring_info & VECTORING_INFO_NESTED_EXCEPTION_MASK, >> event_data); >> break; >> } >> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c >> index 7a55c1eb5297..8546629166e9 100644 >> --- a/arch/x86/kvm/x86.c >> +++ b/arch/x86/kvm/x86.c >> @@ -874,6 +874,11 @@ static void kvm_multiple_exception(struct kvm_vcpu *vcpu, unsigned int nr, >> vcpu->arch.exception.pending = true; >> vcpu->arch.exception.injected = false; >> >> + vcpu->arch.exception.nested = vcpu->arch.exception.nested || >> + (is_fred_enabled(vcpu) && >> + (vcpu->arch.nmi_injected || >> + vcpu->arch.interrupt.injected)); >> + >> vcpu->arch.exception.has_error_code = has_error; >> vcpu->arch.exception.vector = nr; >> vcpu->arch.exception.error_code = error_code; >> @@ -903,8 +908,13 @@ static void kvm_multiple_exception(struct kvm_vcpu *vcpu, unsigned int nr, >> vcpu->arch.exception.injected = false; >> vcpu->arch.exception.pending = false; >> >> + /* #DF is NOT a nested event, per its definition. */ >> + vcpu->arch.exception.nested = false; >> + >> kvm_queue_exception_e(vcpu, DF_VECTOR, 0); >> } else { >> + vcpu->arch.exception.nested = is_fred_enabled(vcpu); >> + >> /* replace previous exception with a new one in a hope >> that instruction re-execution will regenerate lost >> exception */ >