Re: [PATCH v2 3/4] OvmfPkg/PlatformInitLib: dynamic mmio window size

["Fiona Ebner" <f.ebner@proxmox.com>]

Am 04.10.22 um 15:47 schrieb Gerd Hoffmann:
> In case we have a reliable PhysMemAddressWidth use that to dynamically
> size the 64bit address window.  Allocate 1/8 of the physical address
> space and place the window at the upper end of the address space.
> 
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

Hi,
a user recently reported that their Ubuntu 18.04 VM failed to boot after
upgrading to our package based on edk2-stable202302 [0]. While the guest
does reach GRUB, the disk attached via virtio-scsi-pci could not be
found anymore. The user also reported that after changing the bus to
pvscsi, the VM booted again, but the virtual NIC attached via
virtio-net-pci did not work. Changing to e1000 made that work too.

I was able to reproduce the issue (QEMU command line below[1]) and
tracked it down to this patch. I verified that it is still an issue with
current QEMU master and edk2 master, i.e. cafb4f3f36 ("UefiPayloadPkg:
Fix boot shell issue for universal UEFI payload").

The issue happens with -cpu host, but not with -cpu kvm64. My host CPU
is a AMD Ryzen Threadripper 2920X.

"Reverting" with (this was the quickest way)
> diff --git a/OvmfPkg/Library/PlatformInitLib/MemDetect.c b/OvmfPkg/Library/PlatformInitLib/MemDetect.c
> index acf90b4e93..8563d7aedb 100644
> --- a/OvmfPkg/Library/PlatformInitLib/MemDetect.c
> +++ b/OvmfPkg/Library/PlatformInitLib/MemDetect.c
> @@ -855,7 +855,7 @@ PlatformAddressWidthInitialization (
>    PlatformAddressWidthFromCpuid (PlatformInfoHob, TRUE);
>    if (PlatformInfoHob->PhysMemAddressWidth != 0) {
>      // physical address width is known
> -    PlatformDynamicMmioWindow (PlatformInfoHob);
> +    //PlatformDynamicMmioWindow (PlatformInfoHob);^M
>      return;
>    }

allows the disk to be detected again.

The kernel within the VM is
for the user: 4.15.0-210-generic #221-Ubuntu
for me: 4.15.0-211-generic #222-Ubuntu

Happy to provide more information and relevant parts of debug logs.

Best Regards,
Fiona

[0]: https://forum.proxmox.com/threads/127410/#post-557209

[1]: > ./qemu-system-x86_64 \
>   -accel 'kvm' \
>   -chardev 'socket,id=qmp,path=/var/run/qemu-server/113.qmp,server=on,wait=off' \
>   -mon 'chardev=qmp,mode=control' \
>   -pidfile /var/run/qemu-server/113.pid \
>   -drive 'if=pflash,unit=0,format=raw,readonly=on,file=/root/OVMF_CODE.fd' \
>   -drive 'if=pflash,unit=1,id=drive-efidisk0,format=raw,file=/dev/pve/vm-113-disk-2,size=540672' \
>   -nodefaults \
>   -vnc 'unix:/var/run/qemu-server/113.vnc,password=on' \
>   -cpu host \
>   -m 10240 \
>   -device 'pci-bridge,id=pci.3,chassis_nr=3,bus=pci.0,addr=0x5' \
>   -device 'vmware-svga,id=vga,bus=pci.0,addr=0x2' \
>   -device 'virtio-scsi-pci,id=virtioscsi0,bus=pci.3,addr=0x1' \
>   -drive 'file=/dev/pve/vm-113-disk-1,if=none,id=drive-scsi0,format=raw,cache=none,aio=io_uring,detect-zeroes=on' \
>   -device 'scsi-hd,bus=virtioscsi0.0,channel=0,scsi-id=0,lun=0,drive=drive-scsi0,id=scsi0,bootindex=100' \
>   -serial pty \
>   -S \
>   -machine 'type=pc'