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Sean Christopherson a51ed3943e KVM: SVM: Skip WRMSR fastpath on VM-Exit if next RIP isn't valid [ Upstream commit `5c30e8101e` ] Skip the WRMSR fastpath in SVM's VM-Exit handler if the next RIP isn't valid, e.g. because KVM is running with nrips=false. SVM must decode and emulate to skip the WRMSR if the CPU doesn't provide the next RIP. Getting the instruction bytes to decode the WRMSR requires reading guest memory, which in turn means dereferencing memslots, and that isn't safe because KVM doesn't hold SRCU when the fastpath runs. Don't bother trying to enable the fastpath for this case, e.g. by doing only the WRMSR and leaving the "skip" until later. NRIPS is supported on all modern CPUs (KVM has considered making it mandatory), and the next RIP will be valid the vast, vast majority of the time. ============================= WARNING: suspicious RCU usage 6.0.0-smp--4e557fcd3d80-skip #13 Tainted: G O ----------------------------- include/linux/kvm_host.h:954 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 1 lock held by stable/206475: #0: ffff9d9dfebcc0f0 (&vcpu->mutex){+.+.}-{3:3}, at: kvm_vcpu_ioctl+0x8b/0x620 [kvm] stack backtrace: CPU: 152 PID: 206475 Comm: stable Tainted: G O 6.0.0-smp--4e557fcd3d80-skip #13 Hardware name: Google, Inc. Arcadia_IT_80/Arcadia_IT_80, BIOS 10.48.0 01/27/2022 Call Trace: <TASK> dump_stack_lvl+0x69/0xaa dump_stack+0x10/0x12 lockdep_rcu_suspicious+0x11e/0x130 kvm_vcpu_gfn_to_memslot+0x155/0x190 [kvm] kvm_vcpu_gfn_to_hva_prot+0x18/0x80 [kvm] paging64_walk_addr_generic+0x183/0x450 [kvm] paging64_gva_to_gpa+0x63/0xd0 [kvm] kvm_fetch_guest_virt+0x53/0xc0 [kvm] __do_insn_fetch_bytes+0x18b/0x1c0 [kvm] x86_decode_insn+0xf0/0xef0 [kvm] x86_emulate_instruction+0xba/0x790 [kvm] kvm_emulate_instruction+0x17/0x20 [kvm] __svm_skip_emulated_instruction+0x85/0x100 [kvm_amd] svm_skip_emulated_instruction+0x13/0x20 [kvm_amd] handle_fastpath_set_msr_irqoff+0xae/0x180 [kvm] svm_vcpu_run+0x4b8/0x5a0 [kvm_amd] vcpu_enter_guest+0x16ca/0x22f0 [kvm] kvm_arch_vcpu_ioctl_run+0x39d/0x900 [kvm] kvm_vcpu_ioctl+0x538/0x620 [kvm] __se_sys_ioctl+0x77/0xc0 __x64_sys_ioctl+0x1d/0x20 do_syscall_64+0x3d/0x80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Fixes: `404d5d7bff` ("KVM: X86: Introduce more exit_fastpath_completion enum values") Signed-off-by: Sean Christopherson <seanjc@google.com> Link: https://lore.kernel.org/r/20220930234031.1732249-1-seanjc@google.com Signed-off-by: Sasha Levin <sashal@kernel.org>		History 2023-02-25 11:25:40 +01:00
arch	KVM: SVM: Skip WRMSR fastpath on VM-Exit if next RIP isn't valid	2023-02-25 11:25:40 +01:00
block	block, bfq: fix uaf for bfqq in bic_set_bfqq()	2023-02-09 11:28:06 +01:00
certs	certs: Fix build error when PKCS#11 URI contains semicolon	2023-02-09 11:28:11 +01:00
crypto	use less confusing names for iov_iter direction initializers	2023-02-09 11:28:04 +01:00
Documentation	docs: perf: Fix PMU instance name of hisi-pcie-pmu	2023-02-25 11:25:39 +01:00
drivers	spi: mediatek: Enable irq when pdata is ready	2023-02-25 11:25:39 +01:00
fs	revert "squashfs: harden sanity check in squashfs_read_xattr_id_table"	2023-02-22 12:59:50 +01:00
include	scsi: libsas: Add smp_ata_check_ready_type()	2023-02-25 11:25:39 +01:00
init	gcc: disable -Warray-bounds for gcc-11 too	2023-01-14 10:33:43 +01:00
io_uring	use less confusing names for iov_iter direction initializers	2023-02-09 11:28:04 +01:00
ipc	ipc: fix memory leak in init_mqueue_fs()	2022-12-31 13:32:01 +01:00
kernel	sched/psi: Stop relying on timer_pending() for poll_work rescheduling	2023-02-25 11:25:39 +01:00
lib	maple_tree: fix mas_empty_area_rev() lower bound validation	2023-02-09 11:28:23 +01:00
LICENSES	LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers	2021-12-16 14:33:10 +01:00
mm	mm/gup: add folio to list when folio_isolate_lru() succeed	2023-02-22 12:59:54 +01:00
net	net: sched: sch: Fix off by one in htb_activate_prios()	2023-02-22 12:59:56 +01:00
rust	rust: print: avoid evaluating arguments in `pr_*` macros in `unsafe` blocks	2023-02-06 08:06:34 +01:00
samples	ftrace: Export ftrace_free_filter() to modules	2023-02-01 08:34:37 +01:00
scripts	kbuild: modinst: Fix build error when CONFIG_MODULE_SIG_KEY is a PKCS#11 URI	2023-02-09 11:28:11 +01:00
security	use less confusing names for iov_iter direction initializers	2023-02-09 11:28:04 +01:00
sound	ASoC: SOF: Intel: hda-dai: fix possible stream_tag leak	2023-02-22 12:59:56 +01:00
tools	Revert "mm: Always release pages to the buddy allocator in memblock_free_late()."	2023-02-22 12:59:50 +01:00
usr	usr/gen_init_cpio.c: remove unnecessary -1 values from int file	2022-10-03 14:21:44 -07:00
virt	kvm/vfio: Fix potential deadlock on vfio group_lock	2023-02-01 08:34:36 +01:00
.clang-format	inet: ping: use hlist_nulls rcu iterator during lookup	2022-12-01 12:42:46 +01:00
.cocciconfig	scripts: add Linux .cocciconfig for coccinelle	2016-07-22 12:13:39 +02:00
.get_maintainer.ignore	get_maintainer: add Alan to .get_maintainer.ignore	2022-08-20 15:17:44 -07:00
.gitattributes	.gitattributes: use 'dts' diff driver for dts files	2019-12-04 19:44:11 -08:00
.gitignore	Kbuild: add Rust support	2022-09-28 09:02:20 +02:00
.mailmap	9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address	2022-12-10 17:10:52 -08:00
.rustfmt.toml	rust: add `.rustfmt.toml`	2022-09-28 09:02:20 +02:00
COPYING	COPYING: state that all contributions really are covered by this file	2020-02-10 13:32:20 -08:00
CREDITS	MAINTAINERS: Remove Michal Marek from Kbuild maintainers	2022-11-16 14:53:00 +09:00
Kbuild	Kbuild updates for v6.1	2022-10-10 12:00:45 -07:00
Kconfig	kbuild: ensure full rebuild when the compiler is updated	2020-05-12 13:28:33 +09:00
MAINTAINERS	panic: Expose "warn_count" to sysfs	2023-01-24 07:24:41 +01:00
Makefile	Linux 6.1.13	2023-02-22 12:59:56 +01:00
README	Drop all 00-INDEX files from Documentation/	2018-09-09 15:08:58 -06:00

README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.