[PATCH v4 0/3] hw/riscv/virt: pflash improvements

[Sunil V L]

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 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 | 29 +++++++++++++++++++
 hw/riscv/virt.c            | 58 ++++++++++++++++----------------------
 2 files changed, 53 insertions(+), 34 deletions(-)

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2.34.1