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Dexuan Cui db49200b1d video: hyperv_fb: Fix the cache type when mapping the VRAM 
[ Upstream commit 5f1251a48c ]

x86 Hyper-V used to essentially always overwrite the effective cache type
of guest memory accesses to WB. This was problematic in cases where there
is a physical device assigned to the VM, since that often requires that
the VM should have control over cache types. Thus, on newer Hyper-V since
2018, Hyper-V always honors the VM's cache type, but unexpectedly Linux VM
users start to complain that Linux VM's VRAM becomes very slow, and it
turns out that Linux VM should not map the VRAM uncacheable by ioremap().
Fix this slowness issue by using ioremap_cache().

On ARM64, ioremap_cache() is also required as the host also maps the VRAM
cacheable, otherwise VM Connect can't display properly with ioremap() or
ioremap_wc().

With this change, the VRAM on new Hyper-V is as fast as regular RAM, so
it's no longer necessary to use the hacks we added to mitigate the
slowness, i.e. we no longer need to allocate physical memory and use
it to back up the VRAM in Generation-1 VM, and we also no longer need to
allocate physical memory to back up the framebuffer in a Generation-2 VM
and copy the framebuffer to the real VRAM. A further big change will
address these for v5.11.

Fixes: 68a2d20b79 ("drivers/video: add Hyper-V Synthetic Video Frame Buffer Driver")
Tested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Link: https://lore.kernel.org/r/20201118000305.24797-1-decui@microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
 		2020-12-02 08:49:51 +01:00
Documentation xtensa: fix TLBTEMP area placement 2020-11-24 13:29:22 +01:00
LICENSES
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arch ARM: dts: dra76x: m_can: fix order of clocks 2020-12-02 08:49:50 +01:00
block blk-cgroup: Pre-allocate tree node on blkg_conf_prep 2020-11-10 12:37:30 +01:00
certs
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crypto crypto: algif_skcipher - EBUSY on aio should be an error 2020-10-29 09:57:30 +01:00
drivers video: hyperv_fb: Fix the cache type when mapping the VRAM 2020-12-02 08:49:51 +01:00
fs proc: don't allow async path resolution of /proc/self components 2020-12-02 08:49:48 +01:00
include arch: pgtable: define MAX_POSSIBLE_PHYSMEM_BITS where needed 2020-12-02 08:49:50 +01:00
init printk: reduce LOG_BUF_SHIFT range for H8300 2020-11-05 11:43:16 +01:00
ipc ipc/util.c: sysvipc_find_ipc() incorrectly updates position index 2020-05-20 08:20:16 +02:00
kernel sched/fair: Fix overutilized update in enqueue_task_fair() 2020-11-24 13:29:24 +01:00
lib random32: make prandom_u32() output unpredictable 2020-11-18 19:20:20 +01:00
mm mm, page_alloc: skip ->waternark_boost for atomic order-0 allocations 2020-11-24 13:29:24 +01:00
net batman-adv: set .owner to THIS_MODULE 2020-12-02 08:49:50 +01:00
samples samples/bpf: Fix possible deadlock in xdpsock 2020-11-05 11:43:17 +01:00
scripts scripts/setlocalversion: make git describe output more reliable 2020-11-01 12:01:01 +01:00
security selinux: Fix error return code in sel_ib_pkey_sid_slow() 2020-11-18 19:20:30 +01:00
sound ALSA: hda/realtek: Add some Clove SSID in the ALC293(ALC1220) 2020-11-24 13:29:20 +01:00
tools selftests/bpf: Fix error return code in run_getsockopt_test() 2020-11-24 13:29:07 +01:00
usr initramfs: restore default compression behavior 2020-04-08 09:08:38 +02:00
virt KVM: arm64: vgic-v3: Drop the reporting of GICR_TYPER.Last for userspace 2020-12-02 08:49:46 +01:00
.clang-format
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.cocciconfig
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.get_maintainer.ignore
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.gitattributes
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.gitignore
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.mailmap
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COPYING
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CREDITS
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Kbuild
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Kconfig
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MAINTAINERS Documentation/llvm: add documentation on building w/ Clang/LLVM 2020-08-26 10:40:46 +02:00
Makefile Linux 5.4.80 2020-11-24 13:29:24 +01:00
README
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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.