Merge remote-tracking branch 'remotes/alistair/tags/pull-riscv-to-apply-20210715' into staging

Fourth RISC-V PR for 6.1 release

 - Code cleanups
 - Documentation improvements
 - Hypervisor extension improvements with hideleg and hedeleg
 - sifive_u fixes
 - OpenTitan register layout updates
 - Fix coverity issue

# gpg: Signature made Thu 15 Jul 2021 08:14:00 BST
# gpg:                using RSA key F6C4AC46D4934868D3B8CE8F21E10D29DF977054
# gpg: Good signature from "Alistair Francis <alistair@alistair23.me>" [full]
# Primary key fingerprint: F6C4 AC46 D493 4868 D3B8  CE8F 21E1 0D29 DF97 7054

* remotes/alistair/tags/pull-riscv-to-apply-20210715:
  hw/riscv/boot: Check the error of fdt_pack()
  hw/riscv: opentitan: Add the flash alias
  hw/riscv: opentitan: Add the unimplement rv_core_ibex_peri
  char: ibex_uart: Update the register layout
  hw/riscv: sifive_u: Make sure firmware info is 8-byte aligned
  hw/riscv: sifive_u: Correct the CLINT timebase frequency
  docs/system: riscv: Update Microchip Icicle Kit for direct kernel boot
  target/riscv: hardwire bits in hideleg and hedeleg
  docs/system: riscv: Add documentation for virt machine
  docs/system: riscv: Fix CLINT name in the sifive_u doc
  target/riscv: csr: Remove redundant check in fp csr read/write routines
  target/riscv: pmp: Fix some typos

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

4 files changed, 187 insertions, 8 deletions

diff --git a/docs/system/riscv/microchip-icicle-kit.rst b/docs/system/riscv/microchip-icicle-kit.rst
index 54ced661e3..817d2aec9c 100644
--- a/docs/system/riscv/microchip-icicle-kit.rst
+++ b/docs/system/riscv/microchip-icicle-kit.rst
@@ -47,13 +47,13 @@ The user provided DTB should have the following requirements:
 
 QEMU follows below truth table to select which payload to execute:
 
-=====  ========== =======
--bios     -kernel payload
-=====  ========== =======
-    N           N     HSS
-    Y  don't care     HSS
-    N           Y  kernel
-=====  ========== =======
+===== ========== ========== =======
+-bios    -kernel       -dtb payload
+===== ========== ========== =======
+    N          N don't care     HSS
+    Y don't care don't care     HSS
+    N          Y          Y  kernel
+===== ========== ========== =======
 
 The memory is set to 1537 MiB by default which is the minimum required high
 memory size by HSS. A sanity check on ram size is performed in the machine
@@ -106,4 +106,44 @@ HSS output is on the first serial port (stdio) and U-Boot outputs on the
 second serial port. U-Boot will automatically load the Linux kernel from
 the SD card image.
 
+Direct Kernel Boot
+------------------
+
+Sometimes we just want to test booting a new kernel, and transforming the
+kernel image to the format required by the HSS bootflow is tedious. We can
+use '-kernel' for direct kernel booting just like other RISC-V machines do.
+
+In this mode, the OpenSBI fw_dynamic BIOS image for 'generic' platform is
+used to boot an S-mode payload like U-Boot or OS kernel directly.
+
+For example, the following commands show building a U-Boot image from U-Boot
+mainline v2021.07 for the Microchip Icicle Kit board:
+
+.. code-block:: bash
+
+  $ export CROSS_COMPILE=riscv64-linux-
+  $ make microchip_mpfs_icicle_defconfig
+
+Then we can boot the machine by:
+
+.. code-block:: bash
+
+  $ qemu-system-riscv64 -M microchip-icicle-kit -smp 5 -m 2G \
+      -sd path/to/sdcard.img \
+      -nic user,model=cadence_gem \
+      -nic tap,ifname=tap,model=cadence_gem,script=no \
+      -display none -serial stdio \
+      -kernel path/to/u-boot/build/dir/u-boot.bin \
+      -dtb path/to/u-boot/build/dir/u-boot.dtb
+
+CAVEATS:
+
+* Check the "stdout-path" property in the /chosen node in the DTB to determine
+  which serial port is used for the serial console, e.g.: if the console is set
+  to the second serial port, change to use "-serial null -serial stdio".
+* The default U-Boot configuration uses CONFIG_OF_SEPARATE hence the ELF image
+  ``u-boot`` cannot be passed to "-kernel" as it does not contain the DTB hence
+  ``u-boot.bin`` has to be used which does contain one. To use the ELF image,
+  we need to change to CONFIG_OF_EMBED or CONFIG_OF_PRIOR_STAGE.
+
 .. _HSS: https://github.com/polarfire-soc/hart-software-services
diff --git a/docs/system/riscv/sifive_u.rst b/docs/system/riscv/sifive_u.rst
index 32d0a1b85d..01108b5ecc 100644
--- a/docs/system/riscv/sifive_u.rst
+++ b/docs/system/riscv/sifive_u.rst
@@ -11,7 +11,7 @@ The ``sifive_u`` machine supports the following devices:
 
 * 1 E51 / E31 core
 * Up to 4 U54 / U34 cores
-* Core Level Interruptor (CLINT)
+* Core Local Interruptor (CLINT)
 * Platform-Level Interrupt Controller (PLIC)
 * Power, Reset, Clock, Interrupt (PRCI)
 * L2 Loosely Integrated Memory (L2-LIM)
diff --git a/docs/system/riscv/virt.rst b/docs/system/riscv/virt.rst
new file mode 100644
index 0000000000..3709f05797
--- /dev/null
+++ b/docs/system/riscv/virt.rst
@@ -0,0 +1,138 @@
+'virt' Generic Virtual Platform (``virt``)
+==========================================
+
+The `virt` board is a platform which does not correspond to any real hardware;
+it is designed for use in virtual machines. It is the recommended board type
+if you simply want to run a guest such as Linux and do not care about
+reproducing the idiosyncrasies and limitations of a particular bit of
+real-world hardware.
+
+Supported devices
+-----------------
+
+The ``virt`` machine supports the following devices:
+
+* Up to 8 generic RV32GC/RV64GC cores, with optional extensions
+* Core Local Interruptor (CLINT)
+* Platform-Level Interrupt Controller (PLIC)
+* CFI parallel NOR flash memory
+* 1 NS16550 compatible UART
+* 1 Google Goldfish RTC
+* 1 SiFive Test device
+* 8 virtio-mmio transport devices
+* 1 generic PCIe host bridge
+* The fw_cfg device that allows a guest to obtain data from QEMU
+
+Note that the default CPU is a generic RV32GC/RV64GC. Optional extensions
+can be enabled via command line parameters, e.g.: ``-cpu rv64,x-h=true``
+enables the hypervisor extension for RV64.
+
+Hardware configuration information
+----------------------------------
+
+The ``virt`` machine automatically generates a device tree blob ("dtb")
+which it passes to the guest, if there is no ``-dtb`` option. This provides
+information about the addresses, interrupt lines and other configuration of
+the various devices in the system. Guest software should discover the devices
+that are present in the generated DTB.
+
+If users want to provide their own DTB, they can use the ``-dtb`` option.
+These DTBs should have the following requirements:
+
+* The number of subnodes of the /cpus node should match QEMU's ``-smp`` option
+* The /memory reg size should match QEMU’s selected ram_size via ``-m``
+* Should contain a node for the CLINT device with a compatible string
+  "riscv,clint0" if using with OpenSBI BIOS images
+
+Boot options
+------------
+
+The ``virt`` machine can start using the standard -kernel functionality
+for loading a Linux kernel, a VxWorks kernel, an S-mode U-Boot bootloader
+with the default OpenSBI firmware image as the -bios. It also supports
+the recommended RISC-V bootflow: U-Boot SPL (M-mode) loads OpenSBI fw_dynamic
+firmware and U-Boot proper (S-mode), using the standard -bios functionality.
+
+Running Linux kernel
+--------------------
+
+Linux mainline v5.12 release is tested at the time of writing. To build a
+Linux mainline kernel that can be booted by the ``virt`` machine in
+64-bit mode, simply configure the kernel using the defconfig configuration:
+
+.. code-block:: bash
+
+  $ export ARCH=riscv
+  $ export CROSS_COMPILE=riscv64-linux-
+  $ make defconfig
+  $ make
+
+To boot the newly built Linux kernel in QEMU with the ``virt`` machine:
+
+.. code-block:: bash
+
+  $ qemu-system-riscv64 -M virt -smp 4 -m 2G \
+      -display none -serial stdio \
+      -kernel arch/riscv/boot/Image \
+      -initrd /path/to/rootfs.cpio \
+      -append "root=/dev/ram"
+
+To build a Linux mainline kernel that can be booted by the ``virt`` machine
+in 32-bit mode, use the rv32_defconfig configuration. A patch is required to
+fix the 32-bit boot issue for Linux kernel v5.12.
+
+.. code-block:: bash
+
+  $ export ARCH=riscv
+  $ export CROSS_COMPILE=riscv64-linux-
+  $ curl https://patchwork.kernel.org/project/linux-riscv/patch/20210627135117.28641-1-bmeng.cn@gmail.com/mbox/ > riscv.patch
+  $ git am riscv.patch
+  $ make rv32_defconfig
+  $ make
+
+Replace ``qemu-system-riscv64`` with ``qemu-system-riscv32`` in the command
+line above to boot the 32-bit Linux kernel. A rootfs image containing 32-bit
+applications shall be used in order for kernel to boot to user space.
+
+Running U-Boot
+--------------
+
+U-Boot mainline v2021.04 release is tested at the time of writing. To build an
+S-mode U-Boot bootloader that can be booted by the ``virt`` machine, use
+the qemu-riscv64_smode_defconfig with similar commands as described above for Linux:
+
+.. code-block:: bash
+
+  $ export CROSS_COMPILE=riscv64-linux-
+  $ make qemu-riscv64_smode_defconfig
+
+Boot the 64-bit U-Boot S-mode image directly:
+
+.. code-block:: bash
+
+  $ qemu-system-riscv64 -M virt -smp 4 -m 2G \
+      -display none -serial stdio \
+      -kernel /path/to/u-boot.bin
+
+To test booting U-Boot SPL which in M-mode, which in turn loads a FIT image
+that bundles OpenSBI fw_dynamic firmware and U-Boot proper (S-mode) together,
+build the U-Boot images using riscv64_spl_defconfig:
+
+.. code-block:: bash
+
+  $ export CROSS_COMPILE=riscv64-linux-
+  $ export OPENSBI=/path/to/opensbi-riscv64-generic-fw_dynamic.bin
+  $ make qemu-riscv64_spl_defconfig
+
+The minimal QEMU commands to run U-Boot SPL are:
+
+.. code-block:: bash
+
+  $ qemu-system-riscv64 -M virt -smp 4 -m 2G \
+      -display none -serial stdio \
+      -bios /path/to/u-boot-spl \
+      -device loader,file=/path/to/u-boot.itb,addr=0x80200000
+
+To test 32-bit U-Boot images, switch to use qemu-riscv32_smode_defconfig and
+riscv32_spl_defconfig builds, and replace ``qemu-system-riscv64`` with
+``qemu-system-riscv32`` in the command lines above to boot the 32-bit U-Boot.
diff --git a/docs/system/target-riscv.rst b/docs/system/target-riscv.rst
index a5cc06b726..89a866e4f4 100644
--- a/docs/system/target-riscv.rst
+++ b/docs/system/target-riscv.rst
@@ -69,6 +69,7 @@ undocumented; you can get a complete list by running
    riscv/microchip-icicle-kit
    riscv/shakti-c
    riscv/sifive_u
+   riscv/virt
 
 RISC-V CPU firmware
 -------------------