Re: [PATCH v4] KVM: x86: emulate FXSAVE and FXRSTOR

["Radim Krčmář" <rkrcmar@redhat.com>]

2016-11-10 02:42+0800, kbuild test robot:
> Hi Radim,

And I even replied to the series, so this would happen ...
Btw. would the tool recognize it if the header was [PATCH v4 4/4]?

> [auto build test ERROR on kvm/linux-next]
> [also build test ERROR on v4.9-rc4 next-20161109]
> [if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
> 
> url:    https://github.com/0day-ci/linux/commits/Radim-Kr-m/KVM-x86-emulate-FXSAVE-and-FXRSTOR/20161110-021048
> base:   https://git.kernel.org/pub/scm/virt/kvm/kvm.git linux-next
> config: x86_64-randconfig-x018-201645 (attached as .config)
> compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
> reproduce:
>         # save the attached .config to linux build tree
>         make ARCH=x86_64 
> 
> All errors (new ones prefixed by >>):
> 
>    arch/x86/kvm/emulate.c: In function 'em_fxsave':
> >> arch/x86/kvm/emulate.c:3910:7: error: implicit declaration of function 'asm_safe' [-Werror=implicit-function-declaration]
>      rc = asm_safe("fxsave %[fx]", , [fx] "+m"(fx_state));
>           ^~~~~~~~
> >> arch/x86/kvm/emulate.c:3910:32: error: expected expression before ',' token
>      rc = asm_safe("fxsave %[fx]", , [fx] "+m"(fx_state));
>                                    ^
> >> arch/x86/kvm/emulate.c:3910:35: error: 'fx' undeclared (first use in this function)
>      rc = asm_safe("fxsave %[fx]", , [fx] "+m"(fx_state));
>                                       ^~
>    arch/x86/kvm/emulate.c:3910:35: note: each undeclared identifier is reported only once for each function it appears in
>    arch/x86/kvm/emulate.c: In function 'fxrstor_fixup':
>    arch/x86/kvm/emulate.c:3931:32: error: expected expression before ',' token
>      rc = asm_safe("fxsave %[fx]", , [fx] "+m"(old));
>                                    ^
>    arch/x86/kvm/emulate.c:3931:35: error: 'fx' undeclared (first use in this function)
>      rc = asm_safe("fxsave %[fx]", , [fx] "+m"(old));
>                                       ^~
>    arch/x86/kvm/emulate.c: In function 'em_fxrstor':
> >> arch/x86/kvm/emulate.c:3977:34: error: expected expression before ':' token
>       rc = asm_safe("fxrstor %[fx]", : [fx] "m"(fx_state));
>                                      ^
>    arch/x86/kvm/emulate.c: At top level:
> >> arch/x86/kvm/emulate.c:4336:12: error: 'Aligned16' undeclared here (not in a function)
>      I(ModRM | Aligned16, em_fxsave),
>                ^
>    arch/x86/kvm/emulate.c:4185:31: note: in definition of macro 'I'
>     #define I(_f, _e) { .flags = (_f), .u.execute = (_e) }
>                                   ^~
>    cc1: some warnings being treated as errors
> 
> vim +/asm_safe +3910 arch/x86/kvm/emulate.c
> 
>   3904		rc = check_fxsr(ctxt);
>   3905		if (rc != X86EMUL_CONTINUE)
>   3906			return rc;
>   3907	
>   3908		ctxt->ops->get_fpu(ctxt);
>   3909	
> > 3910		rc = asm_safe("fxsave %[fx]", , [fx] "+m"(fx_state));
>   3911	
>   3912		ctxt->ops->put_fpu(ctxt);
>   3913	
>   3914		if (rc != X86EMUL_CONTINUE)
>   3915			return rc;
>   3916	
>   3917		if (ctxt->ops->get_cr(ctxt, 4) & X86_CR4_OSFXSR)
>   3918			size = offsetof(struct fxregs_state, xmm_space[8 * 16/4]);
>   3919		else
>   3920			size = offsetof(struct fxregs_state, xmm_space[0]);
>   3921	
>   3922		return segmented_write(ctxt, ctxt->memop.addr.mem, &fx_state, size);
>   3923	}
>   3924	
>   3925	static int fxrstor_fixup(struct x86_emulate_ctxt *ctxt,
>   3926			struct fxregs_state *new)
>   3927	{
>   3928		int rc = X86EMUL_CONTINUE;
>   3929		struct fxregs_state old;
>   3930	
> > 3931		rc = asm_safe("fxsave %[fx]", , [fx] "+m"(old));
>   3932		if (rc != X86EMUL_CONTINUE)
>   3933			return rc;
>   3934	
>   3935		/*
>   3936		 * 64 bit host will restore XMM 8-15, which is not correct on non-64
>   3937		 * bit guests.  Load the current values in order to preserve 64 bit
>   3938		 * XMMs after fxrstor.
>   3939		 */
>   3940	#ifdef CONFIG_X86_64
>   3941		/* XXX: accessing XMM 8-15 very awkwardly */
>   3942		memcpy(&new->xmm_space[8 * 16/4], &old.xmm_space[8 * 16/4], 8 * 16);
>   3943	#endif
>   3944	
>   3945		/*
>   3946		 * Hardware doesn't save and restore XMM 0-7 without CR4.OSFXSR, but
>   3947		 * does save and restore MXCSR.
>   3948		 */
>   3949		if (!(ctxt->ops->get_cr(ctxt, 4) & X86_CR4_OSFXSR))
>   3950			memcpy(new->xmm_space, old.xmm_space, 8 * 16);
>   3951	
>   3952		return rc;
>   3953	}
>   3954	
>   3955	static int em_fxrstor(struct x86_emulate_ctxt *ctxt)
>   3956	{
>   3957		struct fxregs_state fx_state;
>   3958		int rc;
>   3959	
>   3960		rc = check_fxsr(ctxt);
>   3961		if (rc != X86EMUL_CONTINUE)
>   3962			return rc;
>   3963	
>   3964		rc = segmented_read(ctxt, ctxt->memop.addr.mem, &fx_state, 512);
>   3965		if (rc != X86EMUL_CONTINUE)
>   3966			return rc;
>   3967	
>   3968		if (fx_state.mxcsr >> 16)
>   3969			return emulate_gp(ctxt, 0);
>   3970	
>   3971		ctxt->ops->get_fpu(ctxt);
>   3972	
>   3973		if (ctxt->mode < X86EMUL_MODE_PROT64)
>   3974			rc = fxrstor_fixup(ctxt, &fx_state);
>   3975	
>   3976		if (rc == X86EMUL_CONTINUE)
> > 3977			rc = asm_safe("fxrstor %[fx]", : [fx] "m"(fx_state));
>   3978	
>   3979		ctxt->ops->put_fpu(ctxt);
>   3980	
> 
> ---
> 0-DAY kernel test infrastructure                Open Source Technology Center
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