KVM: SVM: Let gcc to choose which registers to save (x86_64)
This patch lets GCC to determine which registers to save when we switch to/from a VCPU in the case of AMD x86_64. * Original code saves following registers: rbx, rcx, rdx, rsi, rdi, rbp, r8, r9, r10, r11, r12, r13, r14, r15 * Patched code: - informs GCC that we modify following registers using the clobber description: rbx, rcx, rdx, rsi, rdi r8, r9, r10, r11, r12, r13, r14, r15 - rbp is saved (pop/push) because GCC seems to ignore its use in the clobber description. Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net> Signed-off-by: Avi Kivity <avi@qumranet.com>
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@ -1499,10 +1499,7 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
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asm volatile (
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asm volatile (
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#ifdef CONFIG_X86_64
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#ifdef CONFIG_X86_64
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"push %%rbx; push %%rcx; push %%rdx;"
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"push %%rbp; \n\t"
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"push %%rsi; push %%rdi; push %%rbp;"
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"push %%r8; push %%r9; push %%r10; push %%r11;"
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"push %%r12; push %%r13; push %%r14; push %%r15;"
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#else
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#else
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"push %%ebx; push %%ecx; push %%edx;"
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"push %%ebx; push %%ecx; push %%edx;"
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"push %%esi; push %%edi; push %%ebp;"
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"push %%esi; push %%edi; push %%ebp;"
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@ -1567,10 +1564,7 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
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"mov %%r14, %c[r14](%[svm]) \n\t"
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"mov %%r14, %c[r14](%[svm]) \n\t"
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"mov %%r15, %c[r15](%[svm]) \n\t"
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"mov %%r15, %c[r15](%[svm]) \n\t"
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"pop %%r15; pop %%r14; pop %%r13; pop %%r12;"
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"pop %%rbp; \n\t"
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"pop %%r11; pop %%r10; pop %%r9; pop %%r8;"
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"pop %%rbp; pop %%rdi; pop %%rsi;"
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"pop %%rdx; pop %%rcx; pop %%rbx; \n\t"
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#else
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#else
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"mov %%ebx, %c[rbx](%[svm]) \n\t"
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"mov %%ebx, %c[rbx](%[svm]) \n\t"
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"mov %%ecx, %c[rcx](%[svm]) \n\t"
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"mov %%ecx, %c[rcx](%[svm]) \n\t"
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@ -1601,7 +1595,12 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
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[r14]"i"(offsetof(struct vcpu_svm, vcpu.regs[VCPU_REGS_R14])),
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[r14]"i"(offsetof(struct vcpu_svm, vcpu.regs[VCPU_REGS_R14])),
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[r15]"i"(offsetof(struct vcpu_svm, vcpu.regs[VCPU_REGS_R15]))
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[r15]"i"(offsetof(struct vcpu_svm, vcpu.regs[VCPU_REGS_R15]))
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#endif
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#endif
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: "cc", "memory");
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: "cc", "memory"
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#ifdef CONFIG_X86_64
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, "rbx", "rcx", "rdx", "rsi", "rdi"
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, "r8", "r9", "r10", "r11" , "r12", "r13", "r14", "r15"
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#endif
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);
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if ((svm->vmcb->save.dr7 & 0xff))
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if ((svm->vmcb->save.dr7 & 0xff))
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load_db_regs(svm->host_db_regs);
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load_db_regs(svm->host_db_regs);
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