Re: [PATCH kvmtool v2 00/22] Unify I/O port and MMIO trap handling

[Andre Przywara <andre.przywara@arm.com>]

On Tue, 2 Mar 2021 17:57:05 +0000
Alexandru Elisei <alexandru.elisei@arm.com> wrote:

Hi,

> I've started to review this iteration and I've come across this error when trying
> to apply the patches:
> 
> $ git am --reject
> patches/unify-ioport-and-mmio/v2/Unify-I-O-port-and-MMIO-trap-handling.patch
> Applying: ioport: Remove ioport__setup_arch()
> Checking patch arm/ioport.c...
> Checking patch include/kvm/ioport.h...
> Checking patch ioport.c...
> Checking patch mips/kvm.c...
> Checking patch powerpc/ioport.c...
> Checking patch x86/ioport.c...
> Applied patch arm/ioport.c cleanly.
> Applied patch include/kvm/ioport.h cleanly.
> Applied patch ioport.c cleanly.
> Applied patch mips/kvm.c cleanly.
> Applied patch powerpc/ioport.c cleanly.
> Applied patch x86/ioport.c cleanly.
> Applying: hw/serial: Use device abstraction for FDT generator function
> Checking patch hw/serial.c...
> Checking patch include/kvm/kvm.h...
> Applied patch hw/serial.c cleanly.
> Applied patch include/kvm/kvm.h cleanly.
> Applying: ioport: Retire .generate_fdt_node functionality
> Checking patch include/kvm/ioport.h...
> Checking patch ioport.c...
> Applied patch include/kvm/ioport.h cleanly.
> Applied patch ioport.c cleanly.
> Applying: mmio: Extend handling to include ioport emulation
> Checking patch include/kvm/kvm.h...
> Checking patch ioport.c...
> Checking patch mmio.c...
> Applied patch include/kvm/kvm.h cleanly.
> Applied patch ioport.c cleanly.
> Applied patch mmio.c cleanly.
> Applying: hw/i8042: Clean up data types
> Checking patch hw/i8042.c...
> Applied patch hw/i8042.c cleanly.
> Applying: hw/i8042: Refactor trap handler
> Checking patch hw/i8042.c...
> Applied patch hw/i8042.c cleanly.
> Applying: hw/i8042: Switch to new trap handlers
> Checking patch hw/i8042.c...
> error: while searching for:
>         ioport__write8(data, value);
> }
> 
> /*
>  * Called when the OS has written to one of the keyboard's ports (0x60 or 0x64)
>  */
> static bool kbd_in(struct ioport *ioport, struct kvm_cpu *vcpu, u16 port, void
> *data, int size)
> {
>     kbd_io(vcpu, port, data, size, false, NULL);
> 
>     return true;
> }
> 
> static bool kbd_out(struct ioport *ioport, struct kvm_cpu *vcpu, u16 port, void
> *data, int size)
> {
>     kbd_io(vcpu, port, data, size, true, NULL);
> 
>     return true;
> }
> 
> static struct ioport_operations kbd_ops = {
>     .io_in        = kbd_in,
>     .io_out        = kbd_out,
> };
> 
> int kbd__init(struct kvm *kvm)
> {
>     int r;
> 
>     kbd_reset();
>     state.kvm = kvm;
>     r = ioport__register(kvm, I8042_DATA_REG, &kbd_ops, 2, NULL);
>     if (r < 0)
>         return r;
>     r = ioport__register(kvm, I8042_COMMAND_REG, &kbd_ops, 2, NULL);
>     if (r < 0) {
>         ioport__unregister(kvm, I8042_DATA_REG);
>         return r;
>     }
> 
> 
> error: patch failed: hw/i8042.c:325
> Checking patch include/kvm/i8042.h...
> Applying patch hw/i8042.c with 1 reject...
> Rejected hunk #1.
> Applied patch include/kvm/i8042.h cleanly.
> Patch failed at 0007 hw/i8042: Switch to new trap handlers
> hint: Use 'git am --show-current-patch=diff' to see the failed patch
> When you have resolved this problem, run "git am --continue".
> If you prefer to skip this patch, run "git am --skip" instead.
> To restore the original branch and stop patching, run "git am --abort".
> 
> where the patch file is from patchwork.kernel.org [1], created when clicking on
> the "series" button on the top right. I'm not sure what is causing the error,
> everything looks the same to me.

Ah, thanks for the heads up, and sorry for the pain! I can reproduce it,
and see what's going on: I made a last minute change, when creating the
changelog and going over the list of your comments again, and replaced
"false" with 0 in kbd_in() in patch 06/22, but only in the file, not in
the repo. So the follow-up patch - which removes this line again ;-) -
fails to apply.

> Regardless, I've applied the reject manually and everything looks ok.

Oh great, thanks! So I will wait with a resend until you are finished
with the review, and will then also upload to our gitlab.

Apologies for the inconvenience!

Cheers,
Andre


> 
> [1]
> https://patchwork.kernel.org/project/kvm/patch/20210225005915.26423-2-andre.przywara@arm.com/
> 
> Thanks,
> 
> Alex
> 
> On 2/25/21 12:58 AM, Andre Przywara wrote:
> > Compared to v1 this has a few fixes, as suggested by Alex.
> > There is a new patch 20/22, which cleans up the ARM memory map
> > definition and adds some chart to make it more obvious what is going on.
> > For a changelog, see below.
> >
> > ==============
> >
> > At the moment we use two separate code paths to handle exits for
> > KVM_EXIT_IO (ioport.c) and KVM_EXIT_MMIO (mmio.c), even though they
> > are semantically very similar. Because the trap handler callback routine
> > is different, devices need to decide on one conduit or need to provide
> > different handler functions for both of them.
> >
> > This is not only unnecessary code duplication, but makes switching
> > devices from I/O port to MMIO a tedious task, even though there is no
> > real difference between the two, especially on ARM and PowerPC.
> >
> > For ARM we aim at providing a flexible memory layout, and also have
> > trouble with the UART and RTC device overlapping with the PCI I/O area,
> > so it seems indicated to tackle this once and for all.
> >
> > The first three patches do some cleanup, to simplify things later.
> >
> > Patch 04/22 lays the groundwork, by extending mmio.c to be able to also
> > register I/O port trap handlers, using the same callback prototype as
> > we use for MMIO.
> >
> > The next 14 patches then convert devices that use the I/O port
> > interface over to the new joint interface. This requires to rework
> > the trap handler routine to adhere to the same prototype as the existing
> > MMIO handlers. For most devices this is done in two steps: a first to
> > introduce the reworked handler routine, and a second to switch to the new
> > joint registration routine. For some devices the first step is trivial,
> > so it's done in one patch.
> >
> > Patch 19/22 then retires the old I/O port interface, by removing ioport.c
> > and friends.
> > Patch 20/22 uses the opportunity to clean up the memory map description,
> > also declares a new region (from 16MB on), where the final two patches
> > switch the UART and the RTC device to. They are now registered
> > on the MMIO "bus", when running on ARM or arm64. This moves them away
> > from the first 64KB, so they are not in the PCI I/O area anymore.
> >
> > Please have a look and comment!
> >
> > Cheers,
> > Andre
> >
> > Changelog v1 .. v2:
> > - rework memory map definition
> > - add explicit debug output for debug I/O port
> > - add explicit check for MMIO coalescing on I/O ports
> > - drop usage of ioport__{read,write}8() from serial
> > - drop explicit I/O port cleanup routine (to mimic MMIO operation)
> > - add comment for IOTRAP_BUS_MASK
> > - minor cleanups / formatting changes
> >
> > Andre Przywara (22):
> >   ioport: Remove ioport__setup_arch()
> >   hw/serial: Use device abstraction for FDT generator function
> >   ioport: Retire .generate_fdt_node functionality
> >   mmio: Extend handling to include ioport emulation
> >   hw/i8042: Clean up data types
> >   hw/i8042: Refactor trap handler
> >   hw/i8042: Switch to new trap handlers
> >   x86/ioport: Refactor trap handlers
> >   x86/ioport: Switch to new trap handlers
> >   hw/rtc: Refactor trap handlers
> >   hw/rtc: Switch to new trap handler
> >   hw/vesa: Switch trap handling to use MMIO handler
> >   hw/serial: Refactor trap handler
> >   hw/serial: Switch to new trap handlers
> >   vfio: Refactor ioport trap handler
> >   vfio: Switch to new ioport trap handlers
> >   virtio: Switch trap handling to use MMIO handler
> >   pci: Switch trap handling to use MMIO handler
> >   Remove ioport specific routines
> >   arm: Reorganise and document memory map
> >   hw/serial: ARM/arm64: Use MMIO at higher addresses
> >   hw/rtc: ARM/arm64: Use MMIO at higher addresses
> >
> >  Makefile                          |   1 -
> >  arm/include/arm-common/kvm-arch.h |  47 ++++--
> >  arm/ioport.c                      |   5 -
> >  hw/i8042.c                        |  94 +++++-------
> >  hw/rtc.c                          |  91 ++++++------
> >  hw/serial.c                       | 160 ++++++++++++--------
> >  hw/vesa.c                         |  19 +--
> >  include/kvm/i8042.h               |   1 -
> >  include/kvm/ioport.h              |  32 ----
> >  include/kvm/kvm.h                 |  49 ++++++-
> >  ioport.c                          | 235 ------------------------------
> >  mips/kvm.c                        |   5 -
> >  mmio.c                            |  65 +++++++--
> >  pci.c                             |  82 +++--------
> >  powerpc/ioport.c                  |   6 -
> >  vfio/core.c                       |  50 ++++---
> >  virtio/pci.c                      |  46 ++----
> >  x86/ioport.c                      | 107 +++++++-------
> >  18 files changed, 433 insertions(+), 662 deletions(-)
> >  delete mode 100644 ioport.c
> >