Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753513AbbFQJ4e (ORCPT ); Wed, 17 Jun 2015 05:56:34 -0400 Received: from cantor2.suse.de ([195.135.220.15]:33231 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751480AbbFQJ4X (ORCPT ); Wed, 17 Jun 2015 05:56:23 -0400 Date: Wed, 17 Jun 2015 11:56:19 +0200 From: Borislav Petkov To: Andy Lutomirski Cc: x86@kernel.org, Peter Zijlstra , John Stultz , linux-kernel@vger.kernel.org, Len Brown , Huang Rui , Denys Vlasenko , kvm@vger.kernel.org, Ralf Baechle , virtualization@lists.linux-foundation.org Subject: Re: [PATCH v3 03/18] x86/tsc/paravirt: Remove the read_tsc and read_tscp paravirt hooks Message-ID: <20150617095619.GD26661@pd.tnic> References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7477 Lines: 215 + paravirt list. On Tue, Jun 16, 2015 at 05:35:51PM -0700, Andy Lutomirski wrote: > We've had read_tsc and read_tscp paravirt hooks since the very > beginning of paravirt, i.e., d3561b7fa0fb ("[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 > 13426505 1827056 14508032 29761593 1c62039 vmlinux > > After: > text data bss dec hex filename > 13426617 1827056 14508032 29761705 1c620a9 vmlinux > > Signed-off-by: Andy Lutomirski > --- > arch/x86/include/asm/msr.h | 16 ++++++++-------- > arch/x86/include/asm/paravirt.h | 34 ---------------------------------- > arch/x86/include/asm/paravirt_types.h | 2 -- > arch/x86/kernel/paravirt.c | 2 -- > arch/x86/kernel/paravirt_patch_32.c | 2 -- > arch/x86/xen/enlighten.c | 3 --- > 6 files changed, 8 insertions(+), 51 deletions(-) Nice diffstat. Acked-by: Borislav Petkov (leaving in the rest for reference) > diff --git a/arch/x86/include/asm/msr.h b/arch/x86/include/asm/msr.h > index 88711470af7f..d1afac7df484 100644 > --- a/arch/x86/include/asm/msr.h > +++ b/arch/x86/include/asm/msr.h > @@ -178,12 +178,6 @@ static inline int rdmsrl_safe(unsigned msr, unsigned long long *p) > return err; > } > > -#define rdtscl(low) \ > - ((low) = (u32)native_read_tsc()) > - > -#define rdtscll(val) \ > - ((val) = native_read_tsc()) > - > #define rdpmc(counter, low, high) \ > do { \ > u64 _l = native_read_pmc((counter)); \ > @@ -193,6 +187,14 @@ do { \ > > #define rdpmcl(counter, val) ((val) = native_read_pmc(counter)) > > +#endif /* !CONFIG_PARAVIRT */ > + > +#define rdtscl(low) \ > + ((low) = (u32)native_read_tsc()) > + > +#define rdtscll(val) \ > + ((val) = native_read_tsc()) > + > #define rdtscp(low, high, aux) \ > do { \ > unsigned long long _val = native_read_tscp(&(aux)); \ > @@ -202,8 +204,6 @@ do { \ > > #define rdtscpll(val, aux) (val) = native_read_tscp(&(aux)) > > -#endif /* !CONFIG_PARAVIRT */ > - > /* > * 64-bit version of wrmsr_safe(): > */ > diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h > index d143bfad45d7..c2be0375bcad 100644 > --- a/arch/x86/include/asm/paravirt.h > +++ b/arch/x86/include/asm/paravirt.h > @@ -174,19 +174,6 @@ static inline int rdmsrl_safe(unsigned msr, unsigned long long *p) > return err; > } > > -static inline u64 paravirt_read_tsc(void) > -{ > - return PVOP_CALL0(u64, pv_cpu_ops.read_tsc); > -} > - > -#define rdtscl(low) \ > -do { \ > - u64 _l = paravirt_read_tsc(); \ > - low = (int)_l; \ > -} while (0) > - > -#define rdtscll(val) (val = paravirt_read_tsc()) > - > static inline unsigned long long paravirt_sched_clock(void) > { > return PVOP_CALL0(unsigned long long, pv_time_ops.sched_clock); > @@ -215,27 +202,6 @@ do { \ > > #define rdpmcl(counter, val) ((val) = paravirt_read_pmc(counter)) > > -static inline unsigned long long paravirt_rdtscp(unsigned int *aux) > -{ > - return PVOP_CALL1(u64, pv_cpu_ops.read_tscp, aux); > -} > - > -#define rdtscp(low, high, aux) \ > -do { \ > - int __aux; \ > - unsigned long __val = paravirt_rdtscp(&__aux); \ > - (low) = (u32)__val; \ > - (high) = (u32)(__val >> 32); \ > - (aux) = __aux; \ > -} while (0) > - > -#define rdtscpll(val, aux) \ > -do { \ > - unsigned long __aux; \ > - val = paravirt_rdtscp(&__aux); \ > - (aux) = __aux; \ > -} while (0) > - > static inline void paravirt_alloc_ldt(struct desc_struct *ldt, unsigned entries) > { > PVOP_VCALL2(pv_cpu_ops.alloc_ldt, ldt, entries); > diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h > index a6b8f9fadb06..ce029e4fa7c6 100644 > --- a/arch/x86/include/asm/paravirt_types.h > +++ b/arch/x86/include/asm/paravirt_types.h > @@ -156,9 +156,7 @@ struct pv_cpu_ops { > u64 (*read_msr)(unsigned int msr, int *err); > int (*write_msr)(unsigned int msr, unsigned low, unsigned high); > > - u64 (*read_tsc)(void); > u64 (*read_pmc)(int counter); > - unsigned long long (*read_tscp)(unsigned int *aux); > > #ifdef CONFIG_X86_32 > /* > diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c > index 58bcfb67c01f..f68e48f5f6c2 100644 > --- a/arch/x86/kernel/paravirt.c > +++ b/arch/x86/kernel/paravirt.c > @@ -351,9 +351,7 @@ __visible struct pv_cpu_ops pv_cpu_ops = { > .wbinvd = native_wbinvd, > .read_msr = native_read_msr_safe, > .write_msr = native_write_msr_safe, > - .read_tsc = native_read_tsc, > .read_pmc = native_read_pmc, > - .read_tscp = native_read_tscp, > .load_tr_desc = native_load_tr_desc, > .set_ldt = native_set_ldt, > .load_gdt = native_load_gdt, > diff --git a/arch/x86/kernel/paravirt_patch_32.c b/arch/x86/kernel/paravirt_patch_32.c > index e1b013696dde..c89f50a76e97 100644 > --- a/arch/x86/kernel/paravirt_patch_32.c > +++ b/arch/x86/kernel/paravirt_patch_32.c > @@ -10,7 +10,6 @@ DEF_NATIVE(pv_mmu_ops, read_cr2, "mov %cr2, %eax"); > DEF_NATIVE(pv_mmu_ops, write_cr3, "mov %eax, %cr3"); > DEF_NATIVE(pv_mmu_ops, read_cr3, "mov %cr3, %eax"); > DEF_NATIVE(pv_cpu_ops, clts, "clts"); > -DEF_NATIVE(pv_cpu_ops, read_tsc, "rdtsc"); > > #if defined(CONFIG_PARAVIRT_SPINLOCKS) && defined(CONFIG_QUEUED_SPINLOCKS) > DEF_NATIVE(pv_lock_ops, queued_spin_unlock, "movb $0, (%eax)"); > @@ -52,7 +51,6 @@ unsigned native_patch(u8 type, u16 clobbers, void *ibuf, > PATCH_SITE(pv_mmu_ops, read_cr3); > PATCH_SITE(pv_mmu_ops, write_cr3); > PATCH_SITE(pv_cpu_ops, clts); > - PATCH_SITE(pv_cpu_ops, read_tsc); > #if defined(CONFIG_PARAVIRT_SPINLOCKS) && defined(CONFIG_QUEUED_SPINLOCKS) > case PARAVIRT_PATCH(pv_lock_ops.queued_spin_unlock): > if (pv_is_native_spin_unlock()) { > diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c > index 0b95c9b8283f..32136bfca43f 100644 > --- a/arch/x86/xen/enlighten.c > +++ b/arch/x86/xen/enlighten.c > @@ -1175,11 +1175,8 @@ static const struct pv_cpu_ops xen_cpu_ops __initconst = { > .read_msr = xen_read_msr_safe, > .write_msr = xen_write_msr_safe, > > - .read_tsc = native_read_tsc, > .read_pmc = native_read_pmc, > > - .read_tscp = native_read_tscp, > - > .iret = xen_iret, > #ifdef CONFIG_X86_64 > .usergs_sysret32 = xen_sysret32, > -- > 2.4.2 > -- Regards/Gruss, Boris. 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