Date: Mon, 21 May 2018 21:05:55 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r334003 - head/sys/amd64/amd64 Message-ID: <201805212105.w4LL5tGD007344@repo.freebsd.org>
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Author: kib Date: Mon May 21 21:05:55 2018 New Revision: 334003 URL: https://svnweb.freebsd.org/changeset/base/334003 Log: Preserve other bits in IA32_SPEC_CTL MSR when changing the IBRS and STIBP states. Tested by: emaste (previous version) Sponsored by: The FreeBSD Foundation MFC after: 3 days Modified: head/sys/amd64/amd64/support.S Modified: head/sys/amd64/amd64/support.S ============================================================================== --- head/sys/amd64/amd64/support.S Mon May 21 21:04:31 2018 (r334002) +++ head/sys/amd64/amd64/support.S Mon May 21 21:05:55 2018 (r334003) @@ -958,8 +958,9 @@ ENTRY(handle_ibrs_entry) cmpb $0,hw_ibrs_active(%rip) je 1f movl $MSR_IA32_SPEC_CTRL,%ecx - movl $(IA32_SPEC_CTRL_IBRS|IA32_SPEC_CTRL_STIBP),%eax - movl $(IA32_SPEC_CTRL_IBRS|IA32_SPEC_CTRL_STIBP)>>32,%edx + rdmsr + orl $(IA32_SPEC_CTRL_IBRS|IA32_SPEC_CTRL_STIBP),%eax + orl $(IA32_SPEC_CTRL_IBRS|IA32_SPEC_CTRL_STIBP)>>32,%edx wrmsr movb $1,PCPU(IBPB_SET) testl $CPUID_STDEXT_SMEP,cpu_stdext_feature(%rip) @@ -972,8 +973,9 @@ ENTRY(handle_ibrs_exit) cmpb $0,PCPU(IBPB_SET) je 1f movl $MSR_IA32_SPEC_CTRL,%ecx - xorl %eax,%eax - xorl %edx,%edx + rdmsr + andl $~(IA32_SPEC_CTRL_IBRS|IA32_SPEC_CTRL_STIBP),%eax + andl $~((IA32_SPEC_CTRL_IBRS|IA32_SPEC_CTRL_STIBP)>>32),%edx wrmsr movb $0,PCPU(IBPB_SET) 1: ret @@ -987,8 +989,9 @@ ENTRY(handle_ibrs_exit_rs) pushq %rdx pushq %rcx movl $MSR_IA32_SPEC_CTRL,%ecx - xorl %eax,%eax - xorl %edx,%edx + rdmsr + andl $~(IA32_SPEC_CTRL_IBRS|IA32_SPEC_CTRL_STIBP),%eax + andl $~((IA32_SPEC_CTRL_IBRS|IA32_SPEC_CTRL_STIBP)>>32),%edx wrmsr popq %rcx popq %rdx
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