• Andy Lutomirski's avatar
    x86/asm/tsc, x86/paravirt: Remove read_tsc() and read_tscp() paravirt hooks · 9261e050
    Andy Lutomirski authored
    We've had ->read_tsc() and ->read_tscp() paravirt hooks since
    the very beginning of paravirt, i.e.,
    
      d3561b7f ("[PATCH] paravirt: header and stubs for paravirtualisation").
    
    AFAICT, the only paravirt guest implementation that ever
    replaced these calls was vmware, and it's gone. Arguably even
    vmware shouldn't have hooked RDTSC -- we fully support systems
    that don't have a TSC at all, so there's no point for a paravirt
    implementation to pretend that we have a TSC but to replace it.
    
    I also doubt that these hooks actually worked. Calls to rdtscl()
    and rdtscll(), which respected the hooks, were used seemingly
    interchangeably with native_read_tsc(), which did not.
    
    Just remove them. If anyone ever needs them again, they can try
    to make a case for why they need them.
    
    Before, on a paravirt config:
      text    	data     bss     dec     hex filename
      12618257      1816384 1093632 15528273 ecf151 vmlinux
    
    After:
      text		data     bss     dec     hex filename
      12617207      1816384 1093632 15527223 eced37 vmlinux
    Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
    Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
    Cc: Andy Lutomirski <luto@amacapital.net>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Brian Gerst <brgerst@gmail.com>
    Cc: Denys Vlasenko <dvlasenk@redhat.com>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Cc: Huang Rui <ray.huang@amd.com>
    Cc: John Stultz <john.stultz@linaro.org>
    Cc: Len Brown <lenb@kernel.org>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Ralf Baechle <ralf@linux-mips.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: kvm ML <kvm@vger.kernel.org>
    Cc: virtualization@lists.linux-foundation.org
    Link: http://lkml.kernel.org/r/d08a2600fb298af163681e5efd8e599d889a5b97.1434501121.git.luto@kernel.orgSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
    9261e050
msr.h 7.7 KB