716ff017a3
For certain applications it is desirable to rapidly boot a KVM virtual machine. In cases where legacy hardware and software support within the guest is not needed, Qemu should be able to boot directly into the uncompressed Linux kernel binary without the need to run firmware. There already exists an ABI to allow this for Xen PVH guests and the ABI is supported by Linux and FreeBSD: https://xenbits.xen.org/docs/unstable/misc/pvh.html This patch enables Qemu to use that same entry point for booting KVM guests. Signed-off-by: Maran Wilson <maran.wilson@oracle.com> Suggested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Suggested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
138 lines
3.7 KiB
C
138 lines
3.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/acpi.h>
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#include <xen/hvc-console.h>
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#include <asm/io_apic.h>
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#include <asm/hypervisor.h>
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#include <asm/e820/api.h>
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#include <asm/x86_init.h>
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#include <asm/xen/interface.h>
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#include <xen/xen.h>
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#include <xen/interface/hvm/start_info.h>
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/*
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* PVH variables.
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*
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* pvh_bootparams and pvh_start_info need to live in the data segment since
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* they are used after startup_{32|64}, which clear .bss, are invoked.
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*/
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struct boot_params pvh_bootparams __attribute__((section(".data")));
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struct hvm_start_info pvh_start_info __attribute__((section(".data")));
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unsigned int pvh_start_info_sz = sizeof(pvh_start_info);
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static u64 pvh_get_root_pointer(void)
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{
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return pvh_start_info.rsdp_paddr;
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}
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/*
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* Xen guests are able to obtain the memory map from the hypervisor via the
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* HYPERVISOR_memory_op hypercall.
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* If we are trying to boot a Xen PVH guest, it is expected that the kernel
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* will have been configured to provide an override for this routine to do
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* just that.
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*/
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void __init __weak mem_map_via_hcall(struct boot_params *ptr __maybe_unused)
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{
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xen_raw_printk("Error: Could not find memory map\n");
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BUG();
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}
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static void __init init_pvh_bootparams(bool xen_guest)
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{
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memset(&pvh_bootparams, 0, sizeof(pvh_bootparams));
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if ((pvh_start_info.version > 0) && (pvh_start_info.memmap_entries)) {
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struct hvm_memmap_table_entry *ep;
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int i;
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ep = __va(pvh_start_info.memmap_paddr);
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pvh_bootparams.e820_entries = pvh_start_info.memmap_entries;
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for (i = 0; i < pvh_bootparams.e820_entries ; i++, ep++) {
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pvh_bootparams.e820_table[i].addr = ep->addr;
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pvh_bootparams.e820_table[i].size = ep->size;
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pvh_bootparams.e820_table[i].type = ep->type;
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}
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} else if (xen_guest) {
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mem_map_via_hcall(&pvh_bootparams);
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} else {
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/* Non-xen guests are not supported by version 0 */
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BUG();
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}
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if (pvh_bootparams.e820_entries < E820_MAX_ENTRIES_ZEROPAGE - 1) {
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pvh_bootparams.e820_table[pvh_bootparams.e820_entries].addr =
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ISA_START_ADDRESS;
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pvh_bootparams.e820_table[pvh_bootparams.e820_entries].size =
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ISA_END_ADDRESS - ISA_START_ADDRESS;
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pvh_bootparams.e820_table[pvh_bootparams.e820_entries].type =
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E820_TYPE_RESERVED;
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pvh_bootparams.e820_entries++;
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} else
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xen_raw_printk("Warning: Can fit ISA range into e820\n");
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pvh_bootparams.hdr.cmd_line_ptr =
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pvh_start_info.cmdline_paddr;
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/* The first module is always ramdisk. */
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if (pvh_start_info.nr_modules) {
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struct hvm_modlist_entry *modaddr =
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__va(pvh_start_info.modlist_paddr);
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pvh_bootparams.hdr.ramdisk_image = modaddr->paddr;
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pvh_bootparams.hdr.ramdisk_size = modaddr->size;
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}
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/*
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* See Documentation/x86/boot.txt.
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*
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* Version 2.12 supports Xen entry point but we will use default x86/PC
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* environment (i.e. hardware_subarch 0).
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*/
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pvh_bootparams.hdr.version = (2 << 8) | 12;
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pvh_bootparams.hdr.type_of_loader = ((xen_guest ? 0x9 : 0xb) << 4) | 0;
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x86_init.acpi.get_root_pointer = pvh_get_root_pointer;
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}
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/*
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* If we are trying to boot a Xen PVH guest, it is expected that the kernel
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* will have been configured to provide the required override for this routine.
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*/
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void __init __weak xen_pvh_init(void)
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{
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xen_raw_printk("Error: Missing xen PVH initialization\n");
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BUG();
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}
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static void hypervisor_specific_init(bool xen_guest)
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{
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if (xen_guest)
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xen_pvh_init();
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}
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/*
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* This routine (and those that it might call) should not use
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* anything that lives in .bss since that segment will be cleared later.
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*/
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void __init xen_prepare_pvh(void)
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{
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u32 msr = xen_cpuid_base();
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bool xen_guest = !!msr;
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if (pvh_start_info.magic != XEN_HVM_START_MAGIC_VALUE) {
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xen_raw_printk("Error: Unexpected magic value (0x%08x)\n",
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pvh_start_info.magic);
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BUG();
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}
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hypervisor_specific_init(xen_guest);
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init_pvh_bootparams(xen_guest);
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}
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