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[34.168.104.7]) by smtp.gmail.com with ESMTPSA id f5-20020a170902684500b001635b86a790sm13788150pln.44.2022.09.01.07.37.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 01 Sep 2022 07:37:59 -0700 (PDT) Date: Thu, 1 Sep 2022 14:37:56 +0000 From: Sean Christopherson To: Isaku Yamahata Cc: Sagi Shahar , linux-kselftest@vger.kernel.org, Paolo Bonzini , Isaku Yamahata , Erdem Aktas , Ryan Afranji , Roger Wang , Shuah Khan , Andrew Jones , Marc Zyngier , Ben Gardon , Jim Mattson , David Matlack , Peter Xu , Oliver Upton , Ricardo Koller , Yang Zhong , Wei Wang , Xiaoyao Li , Peter Gonda , Marc Orr , Emanuele Giuseppe Esposito , Christian Borntraeger , Eric Auger , Yanan Wang , Aaron Lewis , Vitaly Kuznetsov , Peter Shier , Axel Rasmussen , Zhenzhong Duan , "Maciej S . Szmigiero" , Like Xu , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Subject: Re: [RFC PATCH v2 03/17] KVM: selftest: Adding TDX life cycle test. Message-ID: References: <20220830222000.709028-1-sagis@google.com> <20220830222000.709028-4-sagis@google.com> <20220901004631.GC2711697@ls.amr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20220901004631.GC2711697@ls.amr.corp.intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 31, 2022, Isaku Yamahata wrote: > Sometimes compiler (my gcc is (Ubuntu 11.1.0-1ubuntu1~20.04) 11.1.0) doesn't like > clobering the frame pointer as follows. (I edited the caller site for other test.) > > x86_64/tdx_vm_tests.c:343:1: error: bp cannot be used in ‘asm’ here > > I ended up the following workaround. I didn't use pushq/popq pair because > I didn't want to play with offset in the stack of the caller. > > > diff --git a/tools/testing/selftests/kvm/lib/x86_64/tdx.h b/tools/testing/selftests/kvm/lib/x86_64/tdx.h > index aa6961c6f304..8ddf3b64f003 100644 > --- a/tools/testing/selftests/kvm/lib/x86_64/tdx.h > +++ b/tools/testing/selftests/kvm/lib/x86_64/tdx.h > @@ -122,7 +122,11 @@ void prepare_source_image(struct kvm_vm *vm, void *guest_code, > */ > static inline void tdcall(struct kvm_regs *regs) > { > + unsigned long saved_rbp = 0; > + > asm volatile ( > + /* gcc complains that frame pointer %rbp can't be clobbered. */ > + "movq %%rbp, %28;\n\t" > "mov %13, %%rax;\n\t" > "mov %14, %%rbx;\n\t" > "mov %15, %%rcx;\n\t" > @@ -152,6 +156,8 @@ static inline void tdcall(struct kvm_regs *regs) > "mov %%r15, %10;\n\t" > "mov %%rsi, %11;\n\t" > "mov %%rdi, %12;\n\t" > + "movq %28, %%rbp\n\t" > + "movq $0, %28\n\t" > : "=m" (regs->rax), "=m" (regs->rbx), "=m" (regs->rdx), > "=m" (regs->r8), "=m" (regs->r9), "=m" (regs->r10), > "=m" (regs->r11), "=m" (regs->r12), "=m" (regs->r13), > @@ -161,9 +167,10 @@ static inline void tdcall(struct kvm_regs *regs) > "m" (regs->rdx), "m" (regs->r8), "m" (regs->r9), > "m" (regs->r10), "m" (regs->r11), "m" (regs->r12), > "m" (regs->r13), "m" (regs->r14), "m" (regs->r15), > - "m" (regs->rbp), "m" (regs->rsi), "m" (regs->rdi) > + "m" (regs->rbp), "m" (regs->rsi), "m" (regs->rdi), > + "m" (saved_rbp) > : "rax", "rbx", "rcx", "rdx", "r8", "r9", "r10", "r11", > - "r12", "r13", "r14", "r15", "rbp", "rsi", "rdi"); > + "r12", "r13", "r14", "r15", "rsi", "rdi"); > } Inline assembly for TDCALL is going to be a mess. Assuming proper assembly doesn't Just Work for selftests, we should solve that problem and build this on top.