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From: Borislav Petkov <bp@alien8.de>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
	"Andy Lutomirski" <luto@kernel.org>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	kvm@vger.kernel.org, "Jason A. Donenfeld" <Jason@zx2c4.com>,
	"Rik van Riel" <riel@surriel.com>,
	"Dave Hansen" <dave.hansen@linux.intel.com>,
	"Dave Hansen" <dave.hansen@intel.com>
Subject: Re: [PATCH 12/27] x86/pkru: Provide .*_pkru_ins() functions
Date: Wed, 10 Apr 2019 18:36:15 +0200
Message-ID: <20190410163615.GB26580@zn.tnic> (raw)
In-Reply-To: <20190403164156.19645-13-bigeasy@linutronix.de>

On Wed, Apr 03, 2019 at 06:41:41PM +0200, Sebastian Andrzej Siewior wrote:
> Dave Hansen has asked for __read_pkru() and __write_pkru() to be symmetrical.
> As part of the series __write_pkru() will read back the value and only write it
> if it is different.
> In order to make both functions symmetrical move the function containing only
> the opcode into a function with _isn() suffix. __write_pkru() will just invoke
> __write_pkru_isn() but in a flowup patch will also read back the value.
> 
> Suggested-by: Dave Hansen <dave.hansen@intel.com>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> ---
>  arch/x86/include/asm/pgtable.h       |  2 +-
>  arch/x86/include/asm/special_insns.h | 12 +++++++++---
>  arch/x86/kvm/vmx/vmx.c               |  2 +-
>  3 files changed, 11 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
> index 2779ace16d23f..64333e5222cd9 100644
> --- a/arch/x86/include/asm/pgtable.h
> +++ b/arch/x86/include/asm/pgtable.h
> @@ -127,7 +127,7 @@ static inline int pte_dirty(pte_t pte)
>  static inline u32 read_pkru(void)
>  {
>  	if (boot_cpu_has(X86_FEATURE_OSPKE))
> -		return __read_pkru();
> +		return __read_pkru_ins();
>  	return 0;
>  }
>  
> diff --git a/arch/x86/include/asm/special_insns.h b/arch/x86/include/asm/special_insns.h
> index 43c029cdc3fe8..27328606ff687 100644
> --- a/arch/x86/include/asm/special_insns.h
> +++ b/arch/x86/include/asm/special_insns.h
> @@ -92,7 +92,7 @@ static inline void native_write_cr8(unsigned long val)
>  #endif
>  
>  #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
> -static inline u32 __read_pkru(void)
> +static inline u32 __read_pkru_ins(void)
>  {
>  	u32 ecx = 0;
>  	u32 edx, pkru;
> @@ -107,7 +107,7 @@ static inline u32 __read_pkru(void)
>  	return pkru;
>  }
>  
> -static inline void __write_pkru(u32 pkru)
> +static inline void __write_pkru_ins(u32 pkru)
>  {
>  	u32 ecx = 0, edx = 0;
> 

Well, this is going in the wrong direction. The proper thing to do would
be to have:

rdpkru()
wrpkru()

which only do the inline asm with the respective opcodes. Just like
rdtsc(), clflush(), etc.

IOW, the functions which correspond to the instructions should be called
just like the respective instructions they implement in asm.

Then, all the helpers around them should have different names to denote
what they do. Like the current rdpkru() which does the assertion
checking should be renamed to something like read_pkey_user() or so.
Ditto for the current wrpkru().

Makes sense?

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.

  reply index

Thread overview: 83+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-03 16:41 [PATCH v9 00/27] x86: load FPU registers on return to userland Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 01/27] x86/fpu: Remove fpu->initialized usage in __fpu__restore_sig() Sebastian Andrzej Siewior
2019-04-13 20:46   ` [tip:x86/fpu] " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 02/27] x86/fpu: Remove fpu__restore() Sebastian Andrzej Siewior
2019-04-13 20:47   ` [tip:x86/fpu] " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 03/27] x86/fpu: Remove preempt_disable() in fpu__clear() Sebastian Andrzej Siewior
2019-04-13 20:48   ` [tip:x86/fpu] " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 04/27] x86/fpu: Always init the `state' " Sebastian Andrzej Siewior
2019-04-13 20:48   ` [tip:x86/fpu] x86/fpu: Always init the state " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 05/27] x86/fpu: Remove fpu->initialized usage in copy_fpstate_to_sigframe() Sebastian Andrzej Siewior
2019-04-13 20:49   ` [tip:x86/fpu] " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 06/27] x86/fpu: Don't save fxregs for ia32 frames " Sebastian Andrzej Siewior
2019-04-13 20:50   ` [tip:x86/fpu] " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 07/27] x86/fpu: Remove fpu->initialized Sebastian Andrzej Siewior
2019-04-13 20:50   ` [tip:x86/fpu] " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 08/27] x86/fpu: Remove user_fpu_begin() Sebastian Andrzej Siewior
2019-04-13 20:51   ` [tip:x86/fpu] " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 09/27] x86/fpu: Add (__)make_fpregs_active helpers Sebastian Andrzej Siewior
2019-04-13 20:52   ` [tip:x86/fpu] x86/fpu: Add an __fpregs_load_activate() internal helper tip-bot for Rik van Riel
2019-04-03 16:41 ` [PATCH 10/27] x86/fpu: Make __raw_xsave_addr() use feature number instead of mask Sebastian Andrzej Siewior
2019-04-13 20:52   ` [tip:x86/fpu] x86/fpu: Make __raw_xsave_addr() use a " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 11/27] x86/fpu: Make get_xsave_field_ptr() and get_xsave_addr() use " Sebastian Andrzej Siewior
2019-04-13 20:53   ` [tip:x86/fpu] x86/fpu: Use a feature number instead of mask in two more helpers tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 12/27] x86/pkru: Provide .*_pkru_ins() functions Sebastian Andrzej Siewior
2019-04-10 16:36   ` Borislav Petkov [this message]
2019-04-10 16:52     ` Borislav Petkov
2019-04-10 21:25       ` Sebastian Andrzej Siewior
2019-04-10 21:29         ` Dave Hansen
2019-04-11 13:24           ` Borislav Petkov
2019-04-13 20:54   ` [tip:x86/fpu] x86/pkeys: Provide *pkru() helpers tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 13/27] x86/fpu: Only write PKRU if it is different from current Sebastian Andrzej Siewior
2019-04-13 20:55   ` [tip:x86/fpu] " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 14/27] x86/pkeys: Don't check if PKRU is zero before writting it Sebastian Andrzej Siewior
2019-04-13 20:55   ` [tip:x86/fpu] x86/pkeys: Don't check if PKRU is zero before writing it tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 15/27] x86/fpu: Eager switch PKRU state Sebastian Andrzej Siewior
2019-04-13 20:56   ` [tip:x86/fpu] " tip-bot for Rik van Riel
2019-04-03 16:41 ` [PATCH 16/27] x86/entry: Add TIF_NEED_FPU_LOAD Sebastian Andrzej Siewior
2019-04-13 20:57   ` [tip:x86/fpu] " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 17/27] x86/fpu: Always store the registers in copy_fpstate_to_sigframe() Sebastian Andrzej Siewior
2019-04-13 20:57   ` [tip:x86/fpu] " tip-bot for Rik van Riel
2019-04-03 16:41 ` [PATCH 18/27] x86/fpu: Prepare copy_fpstate_to_sigframe() for TIF_NEED_FPU_LOAD Sebastian Andrzej Siewior
2019-04-13 20:58   ` [tip:x86/fpu] " tip-bot for Rik van Riel
2019-04-03 16:41 ` [PATCH 19/27] x86/fpu: Update xstate's PKRU value on write_pkru() Sebastian Andrzej Siewior
2019-04-08 18:14   ` Dave Hansen
2019-04-08 20:03     ` Sebastian Andrzej Siewior
2019-04-13 20:59   ` [tip:x86/fpu] " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 20/27] x86/fpu: Inline copy_user_to_fpregs_zeroing() Sebastian Andrzej Siewior
2019-04-13 21:00   ` [tip:x86/fpu] " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 21/27] x86/fpu: Let __fpu__restore_sig() restore the !32bit+fxsr frame from kernel memory Sebastian Andrzej Siewior
2019-04-13 21:00   ` [tip:x86/fpu] x86/fpu: Restore from kernel memory on the 64-bit path too tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 22/27] x86/fpu: Merge the two code paths in __fpu__restore_sig() Sebastian Andrzej Siewior
2019-04-13 21:01   ` [tip:x86/fpu] " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 23/27] x86/fpu: Defer FPU state load until return to userspace Sebastian Andrzej Siewior
2019-04-12 14:36   ` Borislav Petkov
2019-04-12 15:24     ` Sebastian Andrzej Siewior
2019-04-12 16:22       ` Borislav Petkov
2019-04-12 16:37         ` Sebastian Andrzej Siewior
2019-04-12 16:48           ` Borislav Petkov
2019-04-12 17:19             ` Sebastian Andrzej Siewior
2019-04-12 17:29               ` Borislav Petkov
2019-04-15  9:14                 ` Sebastian Andrzej Siewior
2019-04-13 21:02   ` [tip:x86/fpu] " tip-bot for Rik van Riel
2019-04-03 16:41 ` [PATCH 24/27] x86/fpu: Add a fastpath to __fpu__restore_sig() Sebastian Andrzej Siewior
2019-04-08 17:05   ` Thomas Gleixner
2019-04-08 20:02     ` Sebastian Andrzej Siewior
2019-04-09  7:27       ` Thomas Gleixner
2019-04-12 17:17   ` Borislav Petkov
2019-04-12 17:27     ` Sebastian Andrzej Siewior
2019-04-13 21:02   ` [tip:x86/fpu] " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 25/27] x86/fpu: Add a fastpath to copy_fpstate_to_sigframe() Sebastian Andrzej Siewior
2019-04-13 21:03   ` [tip:x86/fpu] " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 26/27] x86/fpu: Restore FPU register in copy_fpstate_to_sigframe() in order to use the fastpath Sebastian Andrzej Siewior
2019-04-13 21:04   ` [tip:x86/fpu] x86/fpu: Restore regs " tip-bot for Sebastian Andrzej Siewior
2019-04-03 16:41 ` [PATCH 27/27] x86/pkeys: add PKRU value to init_fpstate Sebastian Andrzej Siewior
2019-04-13 21:05   ` [tip:x86/fpu] x86/pkeys: Add " tip-bot for Sebastian Andrzej Siewior
2019-04-04 14:01 ` [PATCH v9 00/27] x86: load FPU registers on return to userland David Laight
2019-04-04 14:14   ` 'Sebastian Andrzej Siewior'
2019-04-04 14:26     ` Andy Lutomirski
2019-04-04 14:31       ` Sebastian Andrzej Siewior
2019-04-04 15:10       ` David Laight
2019-04-08 17:08 ` Thomas Gleixner
2019-04-12 18:30 ` Borislav Petkov
2019-04-15  8:58   ` Sebastian Andrzej Siewior

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