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Filename Latest commit message Latest commit date
Alexey Kardashevskiy ec5cab3798 KVM: PPC: Fix clearing never mapped TCEs in realmode
[ Upstream commit 1d78dfde33a02da1d816279c2e3452978b7abd39 ]

Since commit e1a1ef84cd ("KVM: PPC: Book3S: Allocate guest TCEs on
demand too"), pages for TCE tables for KVM guests are allocated only
when needed. This allows skipping any update when clearing TCEs. This
works mostly fine as TCE updates are handled when the MMU is enabled.
The realmode handlers fail with H_TOO_HARD when pages are not yet
allocated, except when clearing a TCE in which case KVM prints a warning
and proceeds to dereference a NULL pointer, which crashes the host OS.

This has not been caught so far as the change in commit e1a1ef84cd is
reasonably new, and POWER9 runs mostly radix which does not use realmode
handlers. With hash, the default TCE table is memset() by QEMU when the
machine is reset which triggers page faults and the KVM TCE device's
kvm_spapr_tce_fault() handles those with MMU on. And the huge DMA
windows are not cleared by VMs which instead successfully create a DMA
window big enough to map the VM memory 1:1 and then VMs just map
everything without clearing.

This started crashing now as commit 381ceda88c4c ("powerpc/pseries/iommu:
Make use of DDW for indirect mapping") added a mode when a dymanic DMA
window not big enough to map the VM memory 1:1 but it is used anyway,
and the VM now is the first (i.e. not QEMU) to clear a just created
table. Note that upstream QEMU needs to be modified to trigger the VM to
trigger the host OS crash.

This replaces WARN_ON_ONCE_RM() with a check and return, and adds
another warning if TCE is not being cleared.

Fixes: e1a1ef84cd ("KVM: PPC: Book3S: Allocate guest TCEs on demand too")
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210827040706.517652-1-aik@ozlabs.ru
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-09-22 12:26:25 +02:00
arch KVM: PPC: Fix clearing never mapped TCEs in realmode 2021-09-22 12:26:25 +02:00
block scsi: bsg: Remove support for SCSI_IOCTL_SEND_COMMAND 2021-09-22 12:26:23 +02:00
certs certs: Trigger creation of RSA module signing key if it's not an RSA key 2021-09-15 09:47:29 +02:00
crypto crypto: shash - avoid comparing pointers to exported functions under CFI 2021-07-14 16:53:13 +02:00
Documentation docs: Fix infiniband uverbs minor number 2021-09-22 12:26:23 +02:00
drivers clk: at91: clk-generated: Limit the requested rate to our range 2021-09-22 12:26:25 +02:00
fs fscache: Fix cookie key hashing 2021-09-22 12:26:25 +02:00
include SUNRPC: Fix potential memory corruption 2021-09-22 12:26:24 +02:00
init
ipc
kernel dma-debug: fix debugfs initialization order 2021-09-22 12:26:24 +02:00
lib lib/mpi: use kcalloc in mpi_resize 2021-09-15 09:47:29 +02:00
LICENSES
mm mm/page_alloc: speed up the iteration of max_order 2021-09-12 08:56:41 +02:00
net SUNRPC: Fix potential memory corruption 2021-09-22 12:26:24 +02:00
samples samples/bpf: Fix the error return code of xdp_redirect's main() 2021-07-14 16:53:30 +02:00
scripts scripts/tracing: fix the bug that can't parse raw_trace_func 2021-08-12 13:21:00 +02:00
security IMA: remove the dependency on CRYPTO_MD5 2021-09-15 09:47:41 +02:00
sound ASoC: wcd9335: Disable irq on slave ports in the remove function 2021-09-15 09:47:37 +02:00
tools tools/thermal/tmon: Add cross compiling support 2021-09-22 12:26:20 +02:00
usr
virt KVM: Do not leak memory for duplicate debugfs directories 2021-08-12 13:21:03 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
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Makefile Linux 5.4.147 2021-09-16 12:56:14 +02:00
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.