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Date: Thu, 27 Feb 2020 12:01:22 +0100 From: Alexandre Chartre <alexandre.chartre@...cle.com> To: Thomas Gleixner <tglx@...utronix.de>, LKML <linux-kernel@...r.kernel.org> Cc: x86@...nel.org, Steven Rostedt <rostedt@...dmis.org>, Brian Gerst <brgerst@...il.com>, Juergen Gross <jgross@...e.com>, Paolo Bonzini <pbonzini@...hat.com>, Arnd Bergmann <arnd@...db.de> Subject: Re: [patch 00/10] x86/entry: Consolidation - Part I On 2/25/20 10:36 PM, Thomas Gleixner wrote: > Hi! > > This is the first batch of a 73 patches series which consolidates the x86 > entry code. > > This work started off as a trivial 5 patches series moving the heavy > lifting of POSIX CPU timers out of interrupt context into thread/process > context. This discovered that KVM is lacking to handle pending work items > before entering guest mode and added the handling to the x86 KVM > code. Review requested to make this a generic infrastructure. > > The next series grew to 25 patches implementing the generic infrastructure, > converting x86 (and as a POC ARM64) over, but it turned out that this was > slightly incomplete and still had some entanglement with the rest of the > x86 entry code as some of that functionality is shared between syscall and > interrupt entry/exit. And it also unearthed the nastyness of IOPL which got > already addressed in mainline. > > This series addresses these issues in order to prepare for making the entry > from userspace and exit to userspace (and it's counterpart enter guest) a > generic infrastructure in order to restrict the necessary ASM work to the > bare minimum. > > The series is split into 5 parts: > > - General cleanups and bugfixes > > - Consolidation of the syscall entry/exit code > > - Autogenerate simple exception/trap code and reduce the difference > between 32 and 64 bit > > - Autogenerate complex exception/trap code and provide different entry > points for #DB and #MC exceptions which allows to address the > recently discovered RCU vs. world issues in a more structured way > > - Convert the device interrupt entry code to use the same mechanism as > exceptions and traps and finally convert the system vectors over as > well. The last step after all those cleanups is to move the return > from exception/interrupt logic (user mode work, kernel preemption) > completely from ASM into C-code, so the ASM code just has to take > care about returning from the exception, which is horrible and > convoluted enough already. > > At the end the x86 entry code is ready to move the syscall parts out into > generic code and finally tackle the initial problem which started all of > this. > > The complete series is available from git: > > git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git x86/entry > > which contains all 73 patches. The individual parts are tagged, so this > part can be retrieved via: > > git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git entry-v1-part1 > > Thanks, > > tglx > > 8<--------------- > entry/entry_32.S | 19 +++++++------------ > include/asm/irq.h | 2 +- > include/asm/mce.h | 3 --- > include/asm/traps.h | 17 +++++++---------- > kernel/cpu/mce/core.c | 12 ++++++++++-- > kernel/cpu/mce/internal.h | 3 +++ > kernel/irq.c | 3 +-- > kernel/traps.c | 41 ++++++++++++++++++++++++++++++++++------- > 8 files changed, 63 insertions(+), 37 deletions(-) > For part I: Reviewed-by: Alexandre Chartre <alexandre.chartre@...cle.com> for all patches. I had a slight concern about patch 08 and propagating a different error_code, but I agree with your argument that it is limited to 32-bit process and now matches with the 64-bit behavior. alex.
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