Switch to xen-pvh grub implementation

Our Xen configs don't currently work because xen grub uses a special
code path in grub that does not support zstd compressed kernels. We
switched kernel compression to zstd two years ago. The only grub xen
config that supports this is xen-pvh. Switch our grub xen to the pvh and
adapt configs to run domU in PVH mode.

With this change the pygrub config works.

Signed-off-by: Jeremi Piotrowski <jpiotrowski@microsoft.com>

build_library/build_image_util.sh

@@ -857,7 +857,7 @@ EOF
   # This script must mount the ESP partition differently, so run it after unmount
   if [[ "${install_grub}" -eq 1 ]]; then
     local target
-    local target_list="i386-pc x86_64-efi x86_64-xen"
+    local target_list="i386-pc x86_64-efi i386-xen_pvh"
     if [[ ${BOARD} == "arm64-usr" ]]; then
       target_list="arm64-efi"
     fi

build_library/grub_install.sh

@@ -64,7 +64,7 @@ case "${FLAGS_target}" in
         CORE_NAME="core.efi"
         SBAT_ARG=( --sbat "${BOARD_ROOT}/usr/share/grub/sbat.csv" )
         ;;
-    x86_64-xen)
+    i386-xen_pvh)
         CORE_NAME="core.elf"
         ;;
     arm64-efi)
@@ -234,9 +234,10 @@ case "${FLAGS_target}" in
                 "${FLAGS_copy_shim}"
         fi
         ;;
-    x86_64-xen)
+    i386-xen_pvh)
         info "Installing default x86_64 Xen bootloader."
         sudo mkdir -p "${ESP_DIR}/xen" "${ESP_DIR}/boot/grub"
+        # keep the pvboot name for chainloading?
         sudo cp "${ESP_DIR}/${GRUB_DIR}/${CORE_NAME}" \
             "${ESP_DIR}/xen/pvboot-x86_64.elf"
         sudo cp "${BUILD_LIBRARY_DIR}/menu.lst" \

build_library/vm_image_util.sh

@@ -1004,9 +1004,9 @@ _write_xl_conf() {
     echo 'extra = "(hd0,0)/boot/grub/menu.lst"' >> "${pvgrub}"
 
     # The rest is the same
-    tee -a "${pygrub}" >> "${pvgrub}" <<EOF
+    tee -a "${pygrub}" "${pvgrub}" >/dev/null <<EOF
+type = "pvh"
 
-builder = "generic"
 name = "${VM_NAME}"
 
 memory = "${vm_mem}"

sdk_container/src/third_party/coreos-overlay/profiles/coreos/amd64/make.defaults

@@ -5,4 +5,4 @@ BOOTSTRAP_USE="${BOOTSTRAP_USE} -pax_kernel -xtpax"
 USE="-pax_kernel -urandom -xtpax"
 
 # Enable our assorted Grub targets
-GRUB_PLATFORMS="efi-64 pc xen"
+GRUB_PLATFORMS="efi-64 pc xen-pvh"