qemu/target
Fabiano Rosas 0701abbf98 target/i386: Expose IBPB-BRTYPE and SBPB CPUID bits to the guest
According to AMD's Speculative Return Stack Overflow whitepaper (link
below), the hypervisor should synthesize the value of IBPB_BRTYPE and
SBPB CPUID bits to the guest.

Support for this is already present in the kernel with commit
e47d86083c66 ("KVM: x86: Add SBPB support") and commit 6f0f23ef76be
("KVM: x86: Add IBPB_BRTYPE support").

Add support in QEMU to expose the bits to the guest OS.

host:
  # cat /sys/devices/system/cpu/vulnerabilities/spec_rstack_overflow
  Mitigation: Safe RET

before (guest):
  $ cpuid -l 0x80000021 -1 -r
  0x80000021 0x00: eax=0x00000045 ebx=0x00000000 ecx=0x00000000 edx=0x00000000
                            ^
  $ cat /sys/devices/system/cpu/vulnerabilities/spec_rstack_overflow
  Vulnerable: Safe RET, no microcode

after (guest):
  $ cpuid -l 0x80000021 -1 -r
  0x80000021 0x00: eax=0x18000045 ebx=0x00000000 ecx=0x00000000 edx=0x00000000
                            ^
  $ cat /sys/devices/system/cpu/vulnerabilities/spec_rstack_overflow
  Mitigation: Safe RET

Reported-by: Fabian Vogt <fvogt@suse.de>
Link: https://www.amd.com/content/dam/amd/en/documents/corporate/cr/speculative-return-stack-overflow-whitepaper.pdf
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240805202041.5936-1-farosas@suse.de
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2024-10-03 19:33:23 +02:00
..
alpha license: Update deprecated SPDX tag LGPL-2.0+ to LGPL-2.0-or-later 2024-09-20 10:11:59 +03:00
arm * Convert more Avocado tests to the new functional test framework 2024-09-28 12:34:38 +01:00
avr target: Set TCGCPUOps::cpu_exec_halt to target's has_work implementation 2024-07-11 11:41:34 +01:00
hexagon target/hexagon: Rename macros.inc -> macros.h.inc 2024-09-20 10:07:04 +03:00
hppa license: Update deprecated SPDX tag LGPL-2.0+ to LGPL-2.0-or-later 2024-09-20 10:11:59 +03:00
i386 target/i386: Expose IBPB-BRTYPE and SBPB CPUID bits to the guest 2024-10-03 19:33:23 +02:00
loongarch mark <zlib.h> with for-crc32 in a consistent manner 2024-09-20 08:06:56 +03:00
m68k license: Update deprecated SPDX tag LGPL-2.0+ to LGPL-2.0-or-later 2024-09-20 10:11:59 +03:00
microblaze license: Update deprecated SPDX tag LGPL-2.0+ to LGPL-2.0-or-later 2024-09-20 10:11:59 +03:00
mips license: Update deprecated SPDX tag LGPL-2.0+ to LGPL-2.0-or-later 2024-09-20 10:11:59 +03:00
openrisc license: Update deprecated SPDX tag LGPL-2.0+ to LGPL-2.0-or-later 2024-09-20 10:11:59 +03:00
ppc * Convert more Avocado tests to the new functional test framework 2024-09-28 12:34:38 +01:00
riscv * Convert more Avocado tests to the new functional test framework 2024-09-28 12:34:38 +01:00
rx target/rx: Use target_ulong for address in LI 2024-07-28 14:13:05 +10:00
s390x license: Update deprecated SPDX tag GPL-2.0+ to GPL-2.0-or-later 2024-09-20 10:11:59 +03:00
sh4 license: Update deprecated SPDX tag LGPL-2.0+ to LGPL-2.0-or-later 2024-09-20 10:11:59 +03:00
sparc license: Update deprecated SPDX tag LGPL-2.0+ to LGPL-2.0-or-later 2024-09-20 10:11:59 +03:00
tricore target/tricore: Use unsigned types for bitops in helper_eq_b() 2024-07-29 16:57:27 +01:00
xtensa target/xtensa: Correct assert condition in handle_interrupt() 2024-08-01 10:59:01 +01:00
Kconfig target/cris: Remove the deprecated CRIS target 2024-09-13 20:11:13 +02:00
meson.build target/cris: Remove the deprecated CRIS target 2024-09-13 20:11:13 +02:00