[v11] x86/tdx: Add kexec support

[PATCHv11 00/19] x86/tdx: Add kexec support

Posted by Kirill A. Shutemov 1 year, 6 months ago

The patchset adds bits and pieces to get kexec (and crashkernel) work on
TDX guest.

The last patch implements CPU offlining according to the approved ACPI
spec change poposal[1]. It unlocks kexec with all CPUs visible in the target
kernel. It requires BIOS-side enabling. If it missing we fallback to booting
2nd kernel with single CPU.

Please review. I would be glad for any feedback.

[1] https://lore.kernel.org/all/13356251.uLZWGnKmhe@kreacher

v11:
  - Rebased onto current tip/master;
  - Rename CONFIG_X86_ACPI_MADT_WAKEUP to CONFIG_ACPI_MADT_WAKEUP;
  - Drop CC_ATTR_GUEST_MEM_ENCRYPT checks around x86_platform.guest.enc_kexec_*
    callbacks;
  - Rename x86_platform.guest.enc_kexec_* callbacks;
  - Report error code in case of vmm call fail in __set_memory_enc_pgtable();
  - Update commit messages and comments;
  - Add Reviewed-bys;
v10:
  - Rebased to current tip/master;
  - Preserve CR4.MCE instead of setting it unconditionally;
  - Fix build error in Hyper-V code after rebase;
  - Include Ashish's patch for real;
v9:
  - Rebased;
  - Keep page tables that maps E820_TYPE_ACPI (Ashish);
  - Ack/Reviewed/Tested-bys from Sathya, Kai, Tao;
  - Minor printk() message adjustments;
v8:
  - Rework serialization of around conversion memory back to private;
  - Print ACPI_MADT_TYPE_MULTIPROC_WAKEUP in acpi_table_print_madt_entry();
  - Drop debugfs interface to dump info on shared memory;
  - Adjust comments and commit messages;
  - Reviewed-bys by Baoquan, Dave and Thomas;
v7:
  - Call enc_kexec_stop_conversion() and enc_kexec_unshare_mem() after shutting
    down IO-APIC, lapic and hpet. It meets AMD requirements.
  - Minor style changes;
  - Add Acked/Reviewed-bys;
v6:
  - Rebased to v6.8-rc1;
  - Provide default noop callbacks from .enc_kexec_stop_conversion and
    .enc_kexec_unshare_mem;
  - Split off patch that introduces .enc_kexec_* callbacks;
  - asm_acpi_mp_play_dead(): program CR3 directly from RSI, no MOV to RAX
    required;
  - Restructure how smp_ops.stop_this_cpu() hooked up in crash_nmi_callback();
  - kvmclock patch got merged via KVM tree;
v5:
  - Rename smp_ops.crash_play_dead to smp_ops.stop_this_cpu and use it in
    stop_this_cpu();
  - Split off enc_kexec_stop_conversion() from enc_kexec_unshare_mem();
  - Introduce kernel_ident_mapping_free();
  - Add explicit include for alternatives and stringify.
  - Add barrier() after setting conversion_allowed to false;
  - Mark cpu_hotplug_offline_disabled __ro_after_init;
  - Print error if failed to hand over CPU to BIOS;
  - Update comments and commit messages;
v4:
  - Fix build for !KEXEC_CORE;
  - Cleaner ATLERNATIVE use;
  - Update commit messages and comments;
  - Add Reviewed-bys;
v3:
  - Rework acpi_mp_crash_stop_other_cpus() to avoid invoking hotplug state
    machine;
  - Free page tables if reset vector setup failed;
  - Change asm_acpi_mp_play_dead() to pass reset vector and PGD as arguments;
  - Mark acpi_mp_* variables as static and __ro_after_init;
  - Use u32 for apicid;
  - Disable CPU offlining if reset vector setup failed;
  - Rename madt.S -> madt_playdead.S;
  - Mark tdx_kexec_unshare_mem() as static;
  - Rebase onto up-to-date tip/master;
  - Whitespace fixes;
  - Reorder patches;
  - Add Reviewed-bys;
  - Update comments and commit messages;
v2:
  - Rework how unsharing hook ups into kexec codepath;
  - Rework kvmclock_disable() fix based on Sean's;
  - s/cpu_hotplug_not_supported()/cpu_hotplug_disable_offlining()/;
  - use play_dead_common() to implement acpi_mp_play_dead();
  - cond_resched() in tdx_shared_memory_show();
  - s/target kernel/second kernel/;
  - Update commit messages and comments;

Ashish Kalra (1):
  x86/mm: Do not zap page table entries mapping unaccepted memory table
    during kdump.

Borislav Petkov (1):
  x86/relocate_kernel: Use named labels for less confusion

Kirill A. Shutemov (17):
  x86/acpi: Extract ACPI MADT wakeup code into a separate file
  x86/apic: Mark acpi_mp_wake_* variables as __ro_after_init
  cpu/hotplug: Add support for declaring CPU offlining not supported
  cpu/hotplug, x86/acpi: Disable CPU offlining for ACPI MADT wakeup
  x86/kexec: Keep CR4.MCE set during kexec for TDX guest
  x86/mm: Make x86_platform.guest.enc_status_change_*() return errno
  x86/mm: Return correct level from lookup_address() if pte is none
  x86/tdx: Account shared memory
  x86/mm: Add callbacks to prepare encrypted memory for kexec
  x86/tdx: Convert shared memory back to private on kexec
  x86/mm: Make e820__end_ram_pfn() cover E820_TYPE_ACPI ranges
  x86/acpi: Rename fields in acpi_madt_multiproc_wakeup structure
  x86/acpi: Do not attempt to bring up secondary CPUs in kexec case
  x86/smp: Add smp_ops.stop_this_cpu() callback
  x86/mm: Introduce kernel_ident_mapping_free()
  x86/acpi: Add support for CPU offlining for ACPI MADT wakeup method
  ACPI: tables: Print MULTIPROC_WAKEUP when MADT is parsed

 arch/x86/Kconfig                     |   7 +
 arch/x86/coco/core.c                 |   1 -
 arch/x86/coco/tdx/tdx.c              |  96 ++++++++-
 arch/x86/hyperv/ivm.c                |  22 +-
 arch/x86/include/asm/acpi.h          |   7 +
 arch/x86/include/asm/init.h          |   3 +
 arch/x86/include/asm/pgtable.h       |   5 +
 arch/x86/include/asm/pgtable_types.h |   1 +
 arch/x86/include/asm/set_memory.h    |   3 +
 arch/x86/include/asm/smp.h           |   1 +
 arch/x86/include/asm/x86_init.h      |  13 +-
 arch/x86/kernel/acpi/Makefile        |   1 +
 arch/x86/kernel/acpi/boot.c          |  86 +-------
 arch/x86/kernel/acpi/madt_playdead.S |  28 +++
 arch/x86/kernel/acpi/madt_wakeup.c   | 292 +++++++++++++++++++++++++++
 arch/x86/kernel/crash.c              |  12 ++
 arch/x86/kernel/e820.c               |   9 +-
 arch/x86/kernel/process.c            |   7 +
 arch/x86/kernel/reboot.c             |  18 ++
 arch/x86/kernel/relocate_kernel_64.S |  25 ++-
 arch/x86/kernel/x86_init.c           |   8 +-
 arch/x86/mm/ident_map.c              |  73 +++++++
 arch/x86/mm/init_64.c                |  16 +-
 arch/x86/mm/mem_encrypt_amd.c        |   8 +-
 arch/x86/mm/pat/set_memory.c         |  74 +++++--
 drivers/acpi/tables.c                |  14 ++
 include/acpi/actbl2.h                |  19 +-
 include/linux/cc_platform.h          |  10 -
 include/linux/cpu.h                  |   2 +
 kernel/cpu.c                         |  12 +-
 30 files changed, 707 insertions(+), 166 deletions(-)
 create mode 100644 arch/x86/kernel/acpi/madt_playdead.S
 create mode 100644 arch/x86/kernel/acpi/madt_wakeup.c

-- 
2.43.0

Re: [PATCHv11 00/19] x86/tdx: Add kexec support

Posted by Rafael J. Wysocki 1 year, 6 months ago

On Tue, May 28, 2024 at 11:55 AM Kirill A. Shutemov
<kirill.shutemov@linux.intel.com> wrote:
>
> The patchset adds bits and pieces to get kexec (and crashkernel) work on
> TDX guest.
>
> The last patch implements CPU offlining according to the approved ACPI
> spec change poposal[1]. It unlocks kexec with all CPUs visible in the target
> kernel. It requires BIOS-side enabling. If it missing we fallback to booting
> 2nd kernel with single CPU.
>
> Please review. I would be glad for any feedback.
>
> [1] https://lore.kernel.org/all/13356251.uLZWGnKmhe@kreacher

For the ACPI-related changes in the series

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

[PATCH v7 0/3] x86/snp: Add kexec support

Posted by Ashish Kalra 1 year, 6 months ago

From: Ashish Kalra <ashish.kalra@amd.com>

The patchset adds bits and pieces to get kexec (and crashkernel) work on
SNP guest.

The series is based off of and tested against Kirill Shutemov's tree:
  https://github.com/intel/tdx.git guest-kexec

----

v7:
- Rebased onto current tip/master;
- Moved back to checking the md attribute instead of checking the
  efi_setup for detecting if running under kexec kernel as 
  suggested in upstream review feedback.

v6:
- Updated and restructured the commit message for patch 1/3 to
  explain the issue in detail.
- Updated inline comments in patch 1/3 to explain the issue in 
  detail.
- Moved back to checking efi_setup for detecting if running
  under kexec kernel.

v5:
- Removed sev_es_enabled() function and using sev_status directly to
  check for SEV-ES/SEV-SNP guest.
- used --base option to generate patches to specify Kirill's TDX guest
  kexec patches as prerequisite patches to fix kernel test robot
  build errors.

v4:
- Rebased to current tip/master.
- Reviewed-bys from Sathya.
- Remove snp_kexec_unprep_rom_memory() as it is not needed any more as 
  SEV-SNP code is not validating the ROM range in probe_roms() anymore.
- Fix kernel test robot build error/warnings.

v3:
- Rebased;
- moved Keep page tables that maps E820_TYPE_ACPI patch to Kirill's tdx
  guest kexec patch series.
- checking the md attribute instead of checking the efi_setup for
  detecting if running under kexec kernel.
- added new sev_es_enabled() function.
- skip video memory access in decompressor for SEV-ES/SNP systems to 
  prevent guest termination as boot stage2 #VC handler does not handle
  MMIO.

v2:
- address zeroing of unaccepted memory table mappings at all page table levels
  adding phys_pte_init(), phys_pud_init() and phys_p4d_init().
- include skip efi_arch_mem_reserve() in case of kexec as part of this 
  patch set.
- rename last_address_shd_kexec to a more appropriate 
  kexec_last_address_to_make_private.
- remove duplicate code shared with TDX and use common interfaces
  defined for SNP and TDX for kexec/kdump.
- remove set_pte_enc() dependency on pg_level_to_pfn() and make the 
  function simpler.
- rename unshare_pte() to make_pte_private().
- clarify and make the comment for using kexec_last_address_to_make_private  
  more understandable.
- general cleanup. 

Ashish Kalra (3):
  efi/x86: Fix EFI memory map corruption with kexec
  x86/boot/compressed: Skip Video Memory access in Decompressor for
    SEV-ES/SNP.
  x86/snp: Convert shared memory back to private on kexec

 arch/x86/boot/compressed/misc.c |   6 +-
 arch/x86/include/asm/sev.h      |   4 +
 arch/x86/kernel/sev.c           | 162 ++++++++++++++++++++++++++++++++
 arch/x86/mm/mem_encrypt_amd.c   |   3 +
 arch/x86/platform/efi/quirks.c  |  30 +++++-
 5 files changed, 200 insertions(+), 5 deletions(-)


base-commit: f8441cd55885e43eb0d4e8eedc6c5ab15d2dabf1
prerequisite-patch-id: a911f230c2524bd791c47f62f17f0a93cbf726b6
prerequisite-patch-id: bfe2fa046349978ac1825275eb205acecfbc22f3
prerequisite-patch-id: 5e60d292457c7cd98fd3e45c23127e9463b56a69
prerequisite-patch-id: 1f97d0a2edb7509dd58276f628d1a4bda62c154c
prerequisite-patch-id: 6e07f4d4ac95ad1d2c7750ebd3e87483fb9fd48f
prerequisite-patch-id: 24ec385d6a89cf2c8553c6d29515cc513643a68a
prerequisite-patch-id: 6a8bda2b3cf9bfab8177acdcfc8dd0408ed129fa
prerequisite-patch-id: 99382c42348b9a076ba930eca0dfc9d000ec951d
prerequisite-patch-id: 469a0a3c78b0eca82527cd85e2205fb8fb89d645
prerequisite-patch-id: 2be870cdf58bdc6a10ca3c18bf874e5c6cfb7e42
prerequisite-patch-id: 7fc62697fb6bdade0bab66ba2b45a19759008f9e
prerequisite-patch-id: 95356474298029468750a9c1bc2224fb09a86eed
prerequisite-patch-id: d4966ae63e86d24b0bf578da4dae871cd9002b12
prerequisite-patch-id: fccde6f1fa385b5af0195f81fcb95acd71822428
prerequisite-patch-id: 16048ee15e392b0b9217b8923939b0059311abd2
prerequisite-patch-id: 5c9ae9aa294f72f63ae2c3551507dfbd92525803
prerequisite-patch-id: 758bdb686290c018cbd5b7d005354019f9d15248
prerequisite-patch-id: c85fd0bb6d183a40da73720eaa607481b1d51daf
prerequisite-patch-id: 60760e0c98ab7ccd2ca22ae3e9f20ff5a94c6e91
-- 
2.34.1

[PATCH v7 1/3] efi/x86: Fix EFI memory map corruption with kexec

Posted by Ashish Kalra 1 year, 6 months ago

From: Ashish Kalra <ashish.kalra@amd.com>

With SNP guest kexec observe the following efi memmap corruption :

[    0.000000] efi: EFI v2.7 by EDK II
[    0.000000] efi: SMBIOS=0x7e33f000 SMBIOS 3.0=0x7e33d000 ACPI=0x7e57e000 ACPI 2.0=0x7e57e014 MEMATTR=0x7cc3c018 Unaccepted=0x7c09e018
[    0.000000] efi: [Firmware Bug]: Invalid EFI memory map entries:
[    0.000000] efi: mem03: [type=269370880|attr=0x0e42100e42180e41] range=[0x0486200e41038c18-0x200e898a0eee713ac17] (invalid)
[    0.000000] efi: mem04: [type=12336|attr=0x0e410686300e4105] range=[0x100e420000000176-0x8c290f26248d200e175] (invalid)
[    0.000000] efi: mem06: [type=1124304408|attr=0x000030b400000028] range=[0x0e51300e45280e77-0xb44ed2142f460c1e76] (invalid)
[    0.000000] efi: mem08: [type=68|attr=0x300e540583280e41] range=[0x0000011affff3cd8-0x486200e54b38c0bcd7] (invalid)
[    0.000000] efi: mem10: [type=1107529240|attr=0x0e42280e41300e41] range=[0x300e41058c280e42-0x38010ae54c5c328ee41] (invalid)
[    0.000000] efi: mem11: [type=189335566|attr=0x048d200e42038e18] range=[0x0000318c00000048-0xe42029228ce4200047] (invalid)
[    0.000000] efi: mem12: [type=239142534|attr=0x0000002400000b4b] range=[0x0e41380e0a7d700e-0x80f26238f22bfe500d] (invalid)
[    0.000000] efi: mem14: [type=239207055|attr=0x0e41300e43380e0a] range=[0x8c280e42048d200e-0xc70b028f2f27cc0a00d] (invalid)
[    0.000000] efi: mem15: [type=239210510|attr=0x00080e660b47080e] range=[0x0000324c0000001c-0xa78028634ce490001b] (invalid)
[    0.000000] efi: mem16: [type=4294848528|attr=0x0000329400000014] range=[0x0e410286100e4100-0x80f252036a218f20ff] (invalid)
[    0.000000] efi: mem19: [type=2250772033|attr=0x42180e42200e4328] range=[0x41280e0ab9020683-0xe0e538c28b39e62682] (invalid)
[    0.000000] efi: mem20: [type=16|   |  |  |  |  |  |  |  |  |   |WB|  |WC|  ] range=[0x00000008ffff4438-0xffff44340090333c437] (invalid)
[    0.000000] efi: mem22: [Reserved    |attr=0x000000c1ffff4420] range=[0xffff442400003398-0x1033a04240003f397] (invalid)
[    0.000000] efi: mem23: [type=1141080856|attr=0x080e41100e43180e] range=[0x280e66300e4b280e-0x440dc5ee7141f4c080d] (invalid)
[    0.000000] efi: mem25: [Reserved    |attr=0x0000000affff44a0] range=[0xffff44a400003428-0x1034304a400013427] (invalid)
[    0.000000] efi: mem28: [type=16|   |  |  |  |  |  |  |  |  |   |WB|  |WC|  ] range=[0x0000000affff4488-0xffff448400b034bc487] (invalid)
[    0.000000] efi: mem30: [Reserved    |attr=0x0000000affff4470] range=[0xffff447400003518-0x10352047400013517] (invalid)
[    0.000000] efi: mem33: [type=16|   |  |  |  |  |  |  |  |  |   |WB|  |WC|  ] range=[0x0000000affff4458-0xffff445400b035ac457] (invalid)
[    0.000000] efi: mem35: [type=269372416|attr=0x0e42100e42180e41] range=[0x0486200e44038c18-0x200e8b8a0eee823ac17] (invalid)
[    0.000000] efi: mem37: [type=2351435330|attr=0x0e42100e42180e42] range=[0x470783380e410686-0x2002b2a041c2141e685] (invalid)
[    0.000000] efi: mem38: [type=1093668417|attr=0x100e420000000270] range=[0x42100e42180e4220-0xfff366a4e421b78c21f] (invalid)
[    0.000000] efi: mem39: [type=76357646|attr=0x180e42200e42280e] range=[0x0e410686300e4105-0x4130f251a0710ae5104] (invalid)
[    0.000000] efi: mem40: [type=940444268|attr=0x0e42200e42280e41] range=[0x180e42200e42280e-0x300fc71c300b4f2480d] (invalid)
[    0.000000] efi: mem41: [MMIO        |attr=0x8c280e42048d200e] range=[0xffff479400003728-0x42138e0c87820292727] (invalid)
[    0.000000] efi: mem42: [type=1191674680|attr=0x0000004c0000000b] range=[0x300e41380e0a0246-0x470b0f26238f22b8245] (invalid)
[    0.000000] efi: mem43: [type=2010|attr=0x0301f00e4d078338] range=[0x45038e180e42028f-0xe4556bf118f282528e] (invalid)
[    0.000000] efi: mem44: [type=1109921345|attr=0x300e44000000006c] range=[0x44080e42100e4218-0xfff39254e42138ac217] (invalid)
...

This EFI memap corruption is happening with efi_arch_mem_reserve() invocation in case of kexec boot.

( efi_arch_mem_reserve() is invoked with the following call-stack: )

[    0.310010]  efi_arch_mem_reserve+0xb1/0x220
[    0.311382]  efi_mem_reserve+0x36/0x60
[    0.311973]  efi_bgrt_init+0x17d/0x1a0
[    0.313265]  acpi_parse_bgrt+0x12/0x20
[    0.313858]  acpi_table_parse+0x77/0xd0
[    0.314463]  acpi_boot_init+0x362/0x630
[    0.315069]  setup_arch+0xa88/0xf80
[    0.315629]  start_kernel+0x68/0xa90
[    0.316194]  x86_64_start_reservations+0x1c/0x30
[    0.316921]  x86_64_start_kernel+0xbf/0x110
[    0.317582]  common_startup_64+0x13e/0x141

efi_arch_mem_reserve() calls efi_memmap_alloc() to allocate memory for
EFI memory map and due to early allocation it uses memblock allocation.

Later during boot, efi_enter_virtual_mode() calls kexec_enter_virtual_mode()
in case of a kexec-ed kernel boot.

This function kexec_enter_virtual_mode() installs the new EFI memory map by
calling efi_memmap_init_late() which remaps the efi_memmap physically allocated
in efi_arch_mem_reserve(), but this remapping is still using memblock allocation.

Subsequently, when memblock is freed later in boot flow, this remapped
efi_memmap will have random corruption (similar to a use-after-free scenario).

The corrupted EFI memory map is then passed to the next kexec-ed kernel
which causes a panic when trying to use the corrupted EFI memory map.

Fix this EFI memory map corruption by skipping efi_arch_mem_reserve() for kexec.

Additionally, efi_mem_reserve() is used to reserve boot service memory
eg. bgrt, but it is not necessary for kexec boot, as there are no
boot services in kexec reboot at all after the first kernel ExitBootServices().

The UEFI memmap passed to kexec kernel includes not only the runtime
service memory map but also the boot service memory ranges which were
reserved by the first kernel with efi_mem_reserve, and those boot service
memory ranges have already been marked "EFI_MEMORY_RUNTIME" attribute.

This is the additional reason why efi_mem_reserve can be skipped
for kexec booting and by checking the set EFI_MEMORY_RUNTIME attribute.

Suggested-by: Dave Young <dyoung@redhat.com>
[Dave Young: checking the md attribute instead of checking the efi_setup]
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
---
 arch/x86/platform/efi/quirks.c | 30 +++++++++++++++++++++++++++---
 1 file changed, 27 insertions(+), 3 deletions(-)

diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
index f0cc00032751..6f398c59278a 100644
--- a/arch/x86/platform/efi/quirks.c
+++ b/arch/x86/platform/efi/quirks.c
@@ -255,15 +255,39 @@ void __init efi_arch_mem_reserve(phys_addr_t addr, u64 size)
 	struct efi_memory_map_data data = { 0 };
 	struct efi_mem_range mr;
 	efi_memory_desc_t md;
-	int num_entries;
+	int num_entries, ret;
 	void *new;
 
-	if (efi_mem_desc_lookup(addr, &md) ||
-	    md.type != EFI_BOOT_SERVICES_DATA) {
+	/*
+	 * efi_mem_reserve() is used to reserve boot service memory, eg. bgrt,
+	 * but it is not neccasery for kexec, as there are no boot services in
+	 * kexec reboot at all after the first kernel's ExitBootServices().
+	 *
+	 * Additionally kexec_enter_virtual_mode() during late init will remap
+	 * the efi_memmap physical pages allocated here via memblock & then
+	 * subsequently cause random EFI memmap corruption once memblock is freed.
+	 *
+	 * Therefore, skip efi_mem_reserve for kexec booting by checking the
+	 * EFI_MEMORY_RUNTIME attribute which indicates boot service memory
+	 * ranges reserved by the first kernel using efi_mem_reserve and marked
+	 * with EFI_MEMORY_RUNTIME attribute.
+	 */
+
+	ret = efi_mem_desc_lookup(addr, &md);
+	if (ret) {
 		pr_err("Failed to lookup EFI memory descriptor for %pa\n", &addr);
 		return;
 	}
 
+	if (md.type != EFI_BOOT_SERVICES_DATA) {
+		pr_err("Skip reserving non EFI Boot Service Data memory for %pa\n", &addr);
+		return;
+	}
+
+	/* Kexec copied the efi memmap from the first kernel, thus skip the case */
+	if (md.attribute & EFI_MEMORY_RUNTIME)
+		return;
+
 	if (addr + size > md.phys_addr + (md.num_pages << EFI_PAGE_SHIFT)) {
 		pr_err("Region spans EFI memory descriptors, %pa\n", &addr);
 		return;
-- 
2.34.1