[v6,0/3] hw/riscv/virt: pflash improvements

Message

Sunil V L May 31, 2023, 2:22 p.m. UTC

This series improves the pflash usage in RISC-V virt machine with solutions to
below issues.

1) Currently the first pflash is reserved for ROM/M-mode firmware code. But S-mode
payload firmware like EDK2 need both pflash devices to have separate code and variable
store so that OS distros can keep the FW code as read-only. 

The issue is reported at
https://salsa.debian.org/qemu-team/edk2/-/commit/c345655a0149f64c5020bfc1e53c619ce60587f6

2) The latest way of using pflash devices in other architectures and libvirt
is by using -blockdev and machine options. However, currently this method is
not working in RISC-V.

With above issues fixed, added documentation on how to use pflash devices
in RISC-V virt machine.

This patch series is based on Alistair's riscv-to-apply.next branch.

Changes since v5:
	1) Added KVM use case as per feedback from Anup. Updated the documentation
	   patch that only S-mode payload is supported for KVM guests. Tested with
	   KVM enabled.
	2) Updated tags.

Changes since v4:
	1) Updated patch 2 to avoid accessing private field as per feedback from Philippe.
	2) Updated documentation patch to add read-only for ROM usage.
	3) Rebased to latest riscv-to-apply.next branch and updated tags.

Changes since v3:
	1) Converted single patch to a series with a cover letter since there are
	   multiple patches now.
	2) Added a new patch to enable pflash usage via -blockdev option.
	3) Separated the documentation change into new patch and updated the
	   documentation to mention only -blockdev option which seems to be the
	   recommended way of using pflash.

Changes since v2:
	1) Reverted v2 changes and used v1 approach so that pflash0 can be used
	   for code and pflash1 for variable store.
	2) Rebased to latest riscv-to-apply.next branch.
	3) Added documentation for pflash usage.

Changes since v1:
	1) Simplified the fix such that it doesn't break current EDK2.


Sunil V L (3):
  hw/riscv: virt: Assume M-mode FW in pflash0 only when "-bios none"
  riscv/virt: Support using pflash via -blockdev option
  docs/system: riscv: Add pflash usage details

 docs/system/riscv/virt.rst | 43 +++++++++++++++++++++++++++
 hw/riscv/virt.c            | 59 ++++++++++++++++----------------------
 2 files changed, 68 insertions(+), 34 deletions(-)