On Oct 22, 2007, at 5:24 PM, Laurent Vivier wrote: > Avi Kivity a écrit : >> Laurent Vivier wrote: >>> As x86_64 ABI defines some registers saved by the calling >>> function, it >>> is not >>> needed to save all registers in the called function when >>> switching to >>> VCPU. >>> (see http://www.x86-64.org/documentation/abi.pdf, chapter 3.2.1) >>> >>> The best way to do that is to inform GCC which registers we use >>> and let >>> it to save only needed registers. >>> >>> >> >> Strange, yesterday I started to do the same thing but dropped it >> after I >> got discouraged by reload errors from gcc. > > In french, we say "Les beaux esprits se rencontrent" (Voltaire) ;-) > ("Great minds think alike") > >>> diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c >>> index 2c6b64a..d6c91ac 100644 >>> --- a/drivers/kvm/vmx.c >>> +++ b/drivers/kvm/vmx.c >>> @@ -2243,16 +2243,12 @@ static void vmx_vcpu_run(struct kvm_vcpu >>> *vcpu, struct kvm_run *kvm_run) >>> asm( >>> /* Store host registers */ >>> #ifdef CONFIG_X86_64 >>> - "push %%rax; push %%rbx; push %%rdx;" >>> - "push %%rsi; push %%rdi; push %%rbp;" >>> - "push %%r8; push %%r9; push %%r10; push %%r11;" >>> - "push %%r12; push %%r13; push %%r14; push %%r15;" >>> + "push %%rdx; push %%rbp;" >>> "push %%rcx \n\t" >>> - ASM_VMX_VMWRITE_RSP_RDX "\n\t" >>> #else >>> "pusha; push %%ecx \n\t" >>> - ASM_VMX_VMWRITE_RSP_RDX "\n\t" >>> #endif >>> + ASM_VMX_VMWRITE_RSP_RDX "\n\t" >>> /* Check if vmlaunch of vmresume is needed */ >>> "cmp $0, %1 \n\t" >>> /* Load guest registers. Don't clobber flags. */ >>> @@ -2311,12 +2307,8 @@ static void vmx_vcpu_run(struct kvm_vcpu >>> *vcpu, >>> struct kvm_run *kvm_run) >>> "mov %%r15, %c[r15](%3) \n\t" >>> "mov %%cr2, %%rax \n\t" >>> "mov %%rax, %c[cr2](%3) \n\t" >>> - "mov (%%rsp), %3 \n\t" >>> >>> - "pop %%rcx; pop %%r15; pop %%r14; pop %%r13; pop %% >>> r12;" >>> - "pop %%r11; pop %%r10; pop %%r9; pop %%r8;" >>> - "pop %%rbp; pop %%rdi; pop %%rsi;" >>> - "pop %%rdx; pop %%rbx; pop %%rax \n\t" >>> + "pop %%rcx; pop %%rbp; pop %%rdx \n\t" >>> #else >>> "xchg %3, (%%esp) \n\t" >>> "mov %%eax, %c[rax](%3) \n\t" >>> @@ -2354,7 +2346,12 @@ static void vmx_vcpu_run(struct kvm_vcpu >>> *vcpu, >>> struct kvm_run *kvm_run) >>> [r15]"i"(offsetof(struct kvm_vcpu, regs[VCPU_REGS_R15])), >>> #endif >>> [cr2]"i"(offsetof(struct kvm_vcpu, cr2)) >>> - : "cc", "memory"); >>> + : "cc", "memory", >>> +#ifdef CONFIG_X86_64 >>> + "rbx", "rdi", "rsi", >>> + "r8", "r9", "r10", "r11", "r12", "r13", "r14", "r15" >>> +#endif >>> + ); >>> >> >> The comma after "memory" worries me. Can you compile-test on i386? > > You're right, I thought I've corrected this. I rework this and test > on i386. > >> Other than that the patch is very welcome -- the excessive register >> saving is very annoying to me. > > I think we can do the same thing with svm.c, but I can't test it. >
Actually you can. Recently I implemented SVM emulation capabilities in qemu, so when you use the most current qemu cvs x86_64 emulator, there should be no problem running kvm inside of that. Please mind that it's neither bug-free nor feature-complete but it ran kvm-36 without any problems. Cheers, Alexander Graf ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
