[Qemu-commits] [qemu/qemu] be9c61: xen/pass-through: merge emulated bits correctly

[Richard Henderson]

  Branch: refs/heads/staging
  Home:   https://github.com/qemu/qemu
  Commit: be9c61da9fc57eb7d293f380d0805ca6f46c2657
      
https://github.com/qemu/qemu/commit/be9c61da9fc57eb7d293f380d0805ca6f46c2657
  Author: Chuck Zmudzinski <brchuckz@aol.com>
  Date:   2022-07-05 (Tue, 05 Jul 2022)

  Changed paths:
    M hw/xen/xen_pt_config_init.c

  Log Message:
  -----------
  xen/pass-through: merge emulated bits correctly

In xen_pt_config_reg_init(), there is an error in the merging of the
emulated data with the host value. With the current Qemu, instead of
merging the emulated bits with the host bits as defined by emu_mask,
the emulated bits are merged with the host bits as defined by the
inverse of emu_mask. In some cases, depending on the data in the
registers on the host, the way the registers are setup, and the
initial values of the emulated bits, the end result will be that
the register is initialized with the wrong value.

To correct this error, use the XEN_PT_MERGE_VALUE macro to help ensure
the merge is done correctly.

This correction is needed to resolve Qemu project issue #1061, which
describes the failure of Xen HVM Linux guests to boot in certain
configurations with passed through PCI devices, that is, when this error
disables instead of enables the PCI_STATUS_CAP_LIST bit of the
PCI_STATUS register of a passed through PCI device, which in turn
disables the MSI-X capability of the device in Linux guests with the end
result being that the Linux guest never completes the boot process.

Fixes: 2e87512eccf3 ("xen/pt: Sync up the dev.config and data values")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1061
Buglink: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=988333

Signed-off-by: Chuck Zmudzinski <brchuckz@aol.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
Message-Id: 
<e4392535d8e5266063dc5461d0f1d301e3dd5951.1656522217.git.brchuckz@aol.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>


  Commit: c0e86b7624cb9d6db03e0d48cf82659e5b89a6a6
      
https://github.com/qemu/qemu/commit/c0e86b7624cb9d6db03e0d48cf82659e5b89a6a6
  Author: Chuck Zmudzinski <brchuckz@aol.com>
  Date:   2022-07-05 (Tue, 05 Jul 2022)

  Changed paths:
    M hw/xen/xen_pt_config_init.c

  Log Message:
  -----------
  xen/pass-through: don't create needless register group

Currently we are creating a register group for the Intel IGD OpRegion
for every device we pass through, but the XEN_PCI_INTEL_OPREGION
register group is only valid for an Intel IGD. Add a check to make
sure the device is an Intel IGD and a check that the administrator has
enabled gfx_passthru in the xl domain configuration. Require both checks
to be true before creating the register group. Use the existing
is_igd_vga_passthrough() function to check for a graphics device from
any vendor and that the administrator enabled gfx_passthru in the xl
domain configuration, but further require that the vendor be Intel,
because only Intel IGD devices have an Intel OpRegion. These are the
same checks hvmloader and libxl do to determine if the Intel OpRegion
needs to be mapped into the guest's memory. Also, move the comment
about trapping 0xfc for the Intel OpRegion where it belongs after
applying this patch.

Signed-off-by: Chuck Zmudzinski <brchuckz@aol.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
Message-Id: 
<c76dff6369ccf2256bd9eed5141da1db767293d2.1656480662.git.brchuckz@aol.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>


  Commit: 39e19f5f67d925c60278a6156fd1776d04495a93
      
https://github.com/qemu/qemu/commit/39e19f5f67d925c60278a6156fd1776d04495a93
  Author: Richard Henderson <richard.henderson@linaro.org>
  Date:   2022-07-05 (Tue, 05 Jul 2022)

  Changed paths:
    M hw/xen/xen_pt_config_init.c

  Log Message:
  -----------
  Merge tag 'pull-xen-20220705' of 
https://xenbits.xen.org/git-http/people/aperard/qemu-dm into staging

Xen patches

- Xen PCI passthrough fixes

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# gpg: Signature made Tue 05 Jul 2022 07:14:51 PM +0530
# gpg:                using RSA key F80C006308E22CFD8A92E7980CF5572FD7FB55AF
# gpg: Good signature from "Anthony PERARD <anthony.perard@gmail.com>" [unknown]
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* tag 'pull-xen-20220705' of 
https://xenbits.xen.org/git-http/people/aperard/qemu-dm:
  xen/pass-through: don't create needless register group
  xen/pass-through: merge emulated bits correctly

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>


Compare: https://github.com/qemu/qemu/compare/d82423a69779...39e19f5f67d9