probe_roms() accesses the memory range (0xc0000 - 0x10000) to probe
various ROMs. The memory range is not part of the E820 system RAM range.
The memory range is mapped as private (i.e encrypted) in the page table.
When SEV-SNP is active, all the private memory must be validated before
accessing. The ROM range was not part of E820 map, so the guest BIOS
did not validate it. An access to invalidated memory will cause a
exception yet, so validate the ROM memory regions before it is accessed.
[ bp: Massage commit message. ]
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220307213356.2797205-21-brijesh.singh@amd.com
The encryption attribute for the .bss..decrypted section is cleared in the
initial page table build. This is because the section contains the data
that need to be shared between the guest and the hypervisor.
When SEV-SNP is active, just clearing the encryption attribute in the
page table is not enough. The page state needs to be updated in the RMP
table.
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220307213356.2797205-20-brijesh.singh@amd.com
early_set_memory_{encrypted,decrypted}() are used for changing the page
state from decrypted (shared) to encrypted (private) and vice versa.
When SEV-SNP is active, the page state transition needs to go through
additional steps.
If the page is transitioned from shared to private, then perform the
following after the encryption attribute is set in the page table:
1. Issue the page state change VMGEXIT to add the page as a private
in the RMP table.
2. Validate the page after its successfully added in the RMP table.
To maintain the security guarantees, if the page is transitioned from
private to shared, then perform the following before clearing the
encryption attribute from the page table.
1. Invalidate the page.
2. Issue the page state change VMGEXIT to make the page shared in the
RMP table.
early_set_memory_{encrypted,decrypted}() can be called before the GHCB
is setup so use the SNP page state MSR protocol VMGEXIT defined in the
GHCB specification to request the page state change in the RMP table.
While at it, add a helper snp_prep_memory() which will be used in
probe_roms(), in a later patch.
[ bp: Massage commit message. ]
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Venu Busireddy <venu.busireddy@oracle.com>
Link: https://lore.kernel.org/r/20220307213356.2797205-19-brijesh.singh@amd.com
The SEV-SNP guest is required by the GHCB spec to register the GHCB's
Guest Physical Address (GPA). This is because the hypervisor may prefer
that a guest uses a consistent and/or specific GPA for the GHCB associated
with a vCPU. For more information, see the GHCB specification section
"GHCB GPA Registration".
[ bp: Cleanup comments. ]
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220307213356.2797205-18-brijesh.singh@amd.com
The SEV-SNP guest is required by the GHCB spec to register the GHCB's
Guest Physical Address (GPA). This is because the hypervisor may prefer
that a guest use a consistent and/or specific GPA for the GHCB associated
with a vCPU. For more information, see the GHCB specification section
"GHCB GPA Registration".
If hypervisor can not work with the guest provided GPA then terminate the
guest boot.
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Venu Busireddy <venu.busireddy@oracle.com>
Link: https://lore.kernel.org/r/20220307213356.2797205-17-brijesh.singh@amd.com
Many of the integrity guarantees of SEV-SNP are enforced through the
Reverse Map Table (RMP). Each RMP entry contains the GPA at which a
particular page of DRAM should be mapped. The VMs can request the
hypervisor to add pages in the RMP table via the Page State Change
VMGEXIT defined in the GHCB specification.
Inside each RMP entry is a Validated flag; this flag is automatically
cleared to 0 by the CPU hardware when a new RMP entry is created for a
guest. Each VM page can be either validated or invalidated, as indicated
by the Validated flag in the RMP entry. Memory access to a private page
that is not validated generates a #VC. A VM must use the PVALIDATE
instruction to validate a private page before using it.
To maintain the security guarantee of SEV-SNP guests, when transitioning
pages from private to shared, the guest must invalidate the pages before
asking the hypervisor to change the page state to shared in the RMP table.
After the pages are mapped private in the page table, the guest must
issue a page state change VMGEXIT to mark the pages private in the RMP
table and validate them.
Upon boot, BIOS should have validated the entire system memory.
During the kernel decompression stage, early_setup_ghcb() uses
set_page_decrypted() to make the GHCB page shared (i.e. clear encryption
attribute). And while exiting from the decompression, it calls
set_page_encrypted() to make the page private.
Add snp_set_page_{private,shared}() helpers that are used by
set_page_{decrypted,encrypted}() to change the page state in the RMP
table.
[ bp: Massage commit message and comments. ]
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220307213356.2797205-16-brijesh.singh@amd.com
The Virtual Machine Privilege Level (VMPL) feature in the SEV-SNP
architecture allows a guest VM to divide its address space into four
levels. The level can be used to provide hardware isolated abstraction
layers within a VM. VMPL0 is the highest privilege level, and VMPL3 is
the least privilege level. Certain operations must be done by the VMPL0
software, such as:
* Validate or invalidate memory range (PVALIDATE instruction)
* Allocate VMSA page (RMPADJUST instruction when VMSA=1)
The initial SNP support requires that the guest kernel is running at
VMPL0. Add such a check to verify the guest is running at level 0 before
continuing the boot. There is no easy method to query the current VMPL
level, so use the RMPADJUST instruction to determine whether the guest
is running at the VMPL0.
[ bp: Massage commit message. ]
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220307213356.2797205-15-brijesh.singh@amd.com
An SNP-active guest uses the PVALIDATE instruction to validate or
rescind the validation of a guest page’s RMP entry. Upon completion, a
return code is stored in EAX and rFLAGS bits are set based on the return
code. If the instruction completed successfully, the carry flag (CF)
indicates if the content of the RMP were changed or not.
See AMD APM Volume 3 for additional details.
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Venu Busireddy <venu.busireddy@oracle.com>
Link: https://lore.kernel.org/r/20220307213356.2797205-14-brijesh.singh@amd.com
Version 2 of the GHCB specification added the advertisement of features
that are supported by the hypervisor. If the hypervisor supports SEV-SNP
then it must set the SEV-SNP features bit to indicate that the base
functionality is supported.
Check that feature bit while establishing the GHCB; if failed, terminate
the guest.
Version 2 of the GHCB specification adds several new Non-Automatic Exits
(NAEs), most of them are optional except the hypervisor feature. Now
that the hypervisor feature NAE is implemented, bump the GHCB maximum
supported protocol version.
While at it, move the GHCB protocol negotiation check from the #VC
exception handler to sev_enable() so that all feature detection happens
before the first #VC exception.
While at it, document why the GHCB page cannot be setup from
load_stage2_idt().
[ bp: Massage commit message. ]
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220307213356.2797205-13-brijesh.singh@amd.com
The GHCB specification defines the reason code for reason set 0. The
reason codes defined in the set 0 do not cover all possible causes for a
guest to request termination.
The reason sets 1 to 255 are reserved for the vendor-specific codes.
Reserve the reason set 1 for the Linux guest. Define the error codes for
reason set 1 so that one can have meaningful termination reasons and thus
better guest failure diagnosis.
While at it, change sev_es_terminate() to accept a reason set parameter.
[ bp: Massage commit message. ]
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Venu Busireddy <venu.busireddy@oracle.com>
Link: https://lore.kernel.org/r/20220307213356.2797205-11-brijesh.singh@amd.com
With upcoming SEV-SNP support, SEV-related features need to be
initialized earlier during boot, at the same point the initial #VC
handler is set up, so that the SEV-SNP CPUID table can be utilized
during the initial feature checks. Also, SEV-SNP feature detection
will rely on EFI helper functions to scan the EFI config table for the
Confidential Computing blob, and so would need to be implemented at
least partially in C.
Currently set_sev_encryption_mask() is used to initialize the
sev_status and sme_me_mask globals that advertise what SEV/SME features
are available in a guest. Rename it to sev_enable() to better reflect
that (SME is only enabled in the case of SEV guests in the
boot/compressed kernel), and move it to just after the stage1 #VC
handler is set up so that it can be used to initialize SEV-SNP as well
in future patches.
While at it, re-implement it as C code so that all SEV feature
detection can be better consolidated with upcoming SEV-SNP feature
detection, which will also be in C.
The 32-bit entry path remains unchanged, as it never relied on the
set_sev_encryption_mask() initialization to begin with.
[ bp: Massage commit message. ]
Signed-off-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220307213356.2797205-8-brijesh.singh@amd.com
The current set of helpers used throughout the run-time kernel have
dependencies on code/facilities outside of the boot kernel, so there
are a number of call-sites throughout the boot kernel where inline
assembly is used instead. More will be added with subsequent patches
that add support for SEV-SNP, so take the opportunity to provide a basic
set of helpers that can be used by the boot kernel to reduce reliance on
inline assembly.
Use boot_* prefix so that it's clear these are helpers specific to the
boot kernel to avoid any confusion with the various other MSR read/write
helpers.
[ bp: Disambiguate parameter names and trim comment. ]
Suggested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220307213356.2797205-6-brijesh.singh@amd.com
The initial implementation of the GHCB spec was based on trying to keep
the register state offsets the same relative to the VM save area. However,
the save area for SEV-ES has changed within the hardware causing the
relation between the SEV-ES save area to change relative to the GHCB save
area.
This is the second step in defining the multiple save areas to keep them
separate and ensuring proper operation amongst the different types of
guests. Create a GHCB save area that matches the GHCB specification.
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Venu Busireddy <venu.busireddy@oracle.com>
Link: https://lore.kernel.org/r/20220307213356.2797205-4-brijesh.singh@amd.com
The save area for SEV-ES/SEV-SNP guests, as used by the hardware, is
different from the save area of a non SEV-ES/SEV-SNP guest.
This is the first step in defining the multiple save areas to keep them
separate and ensuring proper operation amongst the different types of
guests. Create an SEV-ES/SEV-SNP save area and adjust usage to the new
save area definition where needed.
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Venu Busireddy <venu.busireddy@oracle.com>
Link: https://lore.kernel.org/r/20220405182743.308853-1-brijesh.singh@amd.com
The hypervisor uses the sev_features field (offset 3B0h) in the Save State
Area to control the SEV-SNP guest features such as SNPActive, vTOM,
ReflectVC etc. An SEV-SNP guest can read the sev_features field through
the SEV_STATUS MSR.
While at it, update dump_vmcb() to log the VMPL level.
See APM2 Table 15-34 and B-4 for more details.
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Venu Busireddy <venu.busireddy@oracle.com>
Link: https://lore.kernel.org/r/20220307213356.2797205-2-brijesh.singh@amd.com
Pull more tracing updates from Steven Rostedt:
- Rename the staging files to give them some meaning. Just
stage1,stag2,etc, does not show what they are for
- Check for NULL from allocation in bootconfig
- Hold event mutex for dyn_event call in user events
- Mark user events to broken (to work on the API)
- Remove eBPF updates from user events
- Remove user events from uapi header to keep it from being installed.
- Move ftrace_graph_is_dead() into inline as it is called from hot
paths and also convert it into a static branch.
* tag 'trace-v5.18-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing: Move user_events.h temporarily out of include/uapi
ftrace: Make ftrace_graph_is_dead() a static branch
tracing: Set user_events to BROKEN
tracing/user_events: Remove eBPF interfaces
tracing/user_events: Hold event_mutex during dyn_event_add
proc: bootconfig: Add null pointer check
tracing: Rename the staging files for trace_events
Pull clk fix from Stephen Boyd:
"A single revert to fix a boot regression seen when clk_put() started
dropping rate range requests. It's best to keep various systems
booting so we'll kick this out and try again next time"
* tag 'clk-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux:
Revert "clk: Drop the rate range on clk_put()"
Pull x86 fixes from Thomas Gleixner:
"A set of x86 fixes and updates:
- Make the prctl() for enabling dynamic XSTATE components correct so
it adds the newly requested feature to the permission bitmap
instead of overwriting it. Add a selftest which validates that.
- Unroll string MMIO for encrypted SEV guests as the hypervisor
cannot emulate it.
- Handle supervisor states correctly in the FPU/XSTATE code so it
takes the feature set of the fpstate buffer into account. The
feature sets can differ between host and guest buffers. Guest
buffers do not contain supervisor states. So far this was not an
issue, but with enabling PASID it needs to be handled in the buffer
offset calculation and in the permission bitmaps.
- Avoid a gazillion of repeated CPUID invocations in by caching the
values early in the FPU/XSTATE code.
- Enable CONFIG_WERROR in x86 defconfig.
- Make the X86 defconfigs more useful by adapting them to Y2022
reality"
* tag 'x86-urgent-2022-04-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/fpu/xstate: Consolidate size calculations
x86/fpu/xstate: Handle supervisor states in XSTATE permissions
x86/fpu/xsave: Handle compacted offsets correctly with supervisor states
x86/fpu: Cache xfeature flags from CPUID
x86/fpu/xsave: Initialize offset/size cache early
x86/fpu: Remove unused supervisor only offsets
x86/fpu: Remove redundant XCOMP_BV initialization
x86/sev: Unroll string mmio with CC_ATTR_GUEST_UNROLL_STRING_IO
x86/config: Make the x86 defconfigs a bit more usable
x86/defconfig: Enable WERROR
selftests/x86/amx: Update the ARCH_REQ_XCOMP_PERM test
x86/fpu/xstate: Fix the ARCH_REQ_XCOMP_PERM implementation
Pull RT signal fix from Thomas Gleixner:
"Revert the RT related signal changes. They need to be reworked and
generalized"
* tag 'core-urgent-2022-04-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
Revert "signal, x86: Delay calling signals in atomic on RT enabled kernels"
Pull more dma-mapping updates from Christoph Hellwig:
- fix a regression in dma remap handling vs AMD memory encryption (me)
- finally kill off the legacy PCI DMA API (Christophe JAILLET)
* tag 'dma-mapping-5.18-1' of git://git.infradead.org/users/hch/dma-mapping:
dma-mapping: move pgprot_decrypted out of dma_pgprot
PCI/doc: cleanup references to the legacy PCI DMA API
PCI: Remove the deprecated "pci-dma-compat.h" API
Pull more perf tools updates from Arnaldo Carvalho de Melo:
- Avoid SEGV if core.cpus isn't set in 'perf stat'.
- Stop depending on .git files for building PERF-VERSION-FILE, used in
'perf --version', fixing some perf tools build scenarios.
- Convert tracepoint.py example to python3.
- Update UAPI header copies from the kernel sources: socket,
mman-common, msr-index, KVM, i915 and cpufeatures.
- Update copy of libbpf's hashmap.c.
- Directly return instead of using local ret variable in
evlist__create_syswide_maps(), found by coccinelle.
* tag 'perf-tools-for-v5.18-2022-04-02' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux:
perf python: Convert tracepoint.py example to python3
perf evlist: Directly return instead of using local ret variable
perf cpumap: More cpu map reuse by merge.
perf cpumap: Add is_subset function
perf evlist: Rename cpus to user_requested_cpus
perf tools: Stop depending on .git files for building PERF-VERSION-FILE
tools headers cpufeatures: Sync with the kernel sources
tools headers UAPI: Sync drm/i915_drm.h with the kernel sources
tools headers UAPI: Sync linux/kvm.h with the kernel sources
tools kvm headers arm64: Update KVM headers from the kernel sources
tools arch x86: Sync the msr-index.h copy with the kernel sources
tools headers UAPI: Sync asm-generic/mman-common.h with the kernel
perf beauty: Update copy of linux/socket.h with the kernel sources
perf tools: Update copy of libbpf's hashmap.c
perf stat: Avoid SEGV if core.cpus isn't set
Pull Kbuild fixes from Masahiro Yamada:
- Fix empty $(PYTHON) expansion.
- Fix UML, which got broken by the attempt to suppress Clang warnings.
- Fix warning message in modpost.
* tag 'kbuild-fixes-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
modpost: restore the warning message for missing symbol versions
Revert "um: clang: Strip out -mno-global-merge from USER_CFLAGS"
kbuild: Remove '-mno-global-merge'
kbuild: fix empty ${PYTHON} in scripts/link-vmlinux.sh
kconfig: remove stale comment about removed kconfig_print_symbol()
Pull MIPS fixes from Thomas Bogendoerfer:
- build fix for gpio
- fix crc32 build problems
- check for failed memory allocations
* tag 'mips_5.18_1' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux:
MIPS: crypto: Fix CRC32 code
MIPS: rb532: move GPIOD definition into C-files
MIPS: lantiq: check the return value of kzalloc()
mips: sgi-ip22: add a check for the return of kzalloc()
Pull kvm fixes from Paolo Bonzini:
- Only do MSR filtering for MSRs accessed by rdmsr/wrmsr
- Documentation improvements
- Prevent module exit until all VMs are freed
- PMU Virtualization fixes
- Fix for kvm_irq_delivery_to_apic_fast() NULL-pointer dereferences
- Other miscellaneous bugfixes
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (42 commits)
KVM: x86: fix sending PV IPI
KVM: x86/mmu: do compare-and-exchange of gPTE via the user address
KVM: x86: Remove redundant vm_entry_controls_clearbit() call
KVM: x86: cleanup enter_rmode()
KVM: x86: SVM: fix tsc scaling when the host doesn't support it
kvm: x86: SVM: remove unused defines
KVM: x86: SVM: move tsc ratio definitions to svm.h
KVM: x86: SVM: fix avic spec based definitions again
KVM: MIPS: remove reference to trap&emulate virtualization
KVM: x86: document limitations of MSR filtering
KVM: x86: Only do MSR filtering when access MSR by rdmsr/wrmsr
KVM: x86/emulator: Emulate RDPID only if it is enabled in guest
KVM: x86/pmu: Fix and isolate TSX-specific performance event logic
KVM: x86: mmu: trace kvm_mmu_set_spte after the new SPTE was set
KVM: x86/svm: Clear reserved bits written to PerfEvtSeln MSRs
KVM: x86: Trace all APICv inhibit changes and capture overall status
KVM: x86: Add wrappers for setting/clearing APICv inhibits
KVM: x86: Make APICv inhibit reasons an enum and cleanup naming
KVM: X86: Handle implicit supervisor access with SMAP
KVM: X86: Rename variable smap to not_smap in permission_fault()
...
Pull block driver fix from Jens Axboe:
"Got two reports on nbd spewing warnings on load now, which is a
regression from a commit that went into your tree yesterday.
Revert the problematic change for now"
* tag 'for-5.18/drivers-2022-04-02' of git://git.kernel.dk/linux-block:
Revert "nbd: fix possible overflow on 'first_minor' in nbd_dev_add()"
Pull pci fix from Bjorn Helgaas:
- Fix Hyper-V "defined but not used" build issue added during merge
window (YueHaibing)
* tag 'pci-v5.18-changes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci:
PCI: hv: Remove unused hv_set_msi_entry_from_desc()
Pull chrome platform updates from Benson Leung:
"cros_ec_typec:
- Check for EC device - Fix a crash when using the cros_ec_typec
driver on older hardware not capable of typec commands
- Make try power role optional
- Mux configuration reorganization series from Prashant
cros_ec_debugfs:
- Fix use after free. Thanks Tzung-bi
sensorhub:
- cros_ec_sensorhub fixup - Split trace include file
misc:
- Add new mailing list for chrome-platform development:
chrome-platform@lists.linux.dev
Now with patchwork!"
* tag 'tag-chrome-platform-for-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/chrome-platform/linux:
platform/chrome: cros_ec_debugfs: detach log reader wq from devm
platform: chrome: Split trace include file
platform/chrome: cros_ec_typec: Update mux flags during partner removal
platform/chrome: cros_ec_typec: Configure muxes at start of port update
platform/chrome: cros_ec_typec: Get mux state inside configure_mux
platform/chrome: cros_ec_typec: Move mux flag checks
platform/chrome: cros_ec_typec: Check for EC device
platform/chrome: cros_ec_typec: Make try power role optional
MAINTAINERS: platform-chrome: Add new chrome-platform@lists.linux.dev list
This reverts commit 6d35d04a9e.
Both Gabriel and Borislav report that this commit casues a regression
with nbd:
sysfs: cannot create duplicate filename '/dev/block/43:0'
Revert it before 5.18-rc1 and we'll investigage this separately in
due time.
Link: https://lore.kernel.org/all/YkiJTnFOt9bTv6A2@zn.tnic/
Reported-by: Gabriel L. Somlo <somlo@cmu.edu>
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
After being merged, user_events become more visible to a wider audience
that have concerns with the current API.
It is too late to fix this for this release, but instead of a full
revert, just mark it as BROKEN (which prevents it from being selected in
make config). Then we can work finding a better API. If that fails,
then it will need to be completely reverted.
To not have the code silently bitrot, still allow building it with
COMPILE_TEST.
And to prevent the uapi header from being installed, then later changed,
and then have an old distro user space see the old version, move the
header file out of the uapi directory.
Surround the include with CONFIG_COMPILE_TEST to the current location,
but when the BROKEN tag is taken off, it will use the uapi directory,
and fail to compile. This is a good way to remind us to move the header
back.
Link: https://lore.kernel.org/all/20220330155835.5e1f6669@gandalf.local.home
Link: https://lkml.kernel.org/r/20220330201755.29319-1-mathieu.desnoyers@efficios.com
Suggested-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
ftrace_graph_is_dead() is used on hot paths, it just reads a variable
in memory and is not worth suffering function call constraints.
For instance, at entry of prepare_ftrace_return(), inlining it avoids
saving prepare_ftrace_return() parameters to stack and restoring them
after calling ftrace_graph_is_dead().
While at it using a static branch is even more performant and is
rather well adapted considering that the returned value will almost
never change.
Inline ftrace_graph_is_dead() and replace 'kill_ftrace_graph' bool
by a static branch.
The performance improvement is noticeable.
Link: https://lkml.kernel.org/r/e0411a6a0ed3eafff0ad2bc9cd4b0e202b4617df.1648623570.git.christophe.leroy@csgroup.eu
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
When looking for implementation of different phases of the creation of the
TRACE_EVENT() macro, it is pretty useless when all helper macro
redefinitions are in files labeled "stageX_defines.h". Rename them to
state which phase the files are for. For instance, when looking for the
defines that are used to create the event fields, seeing
"stage4_event_fields.h" gives the developer a good idea that the defines
are in that file.
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
If apic_id is less than min, and (max - apic_id) is greater than
KVM_IPI_CLUSTER_SIZE, then the third check condition is satisfied but
the new apic_id does not fit the bitmask. In this case __send_ipi_mask
should send the IPI.
This is mostly theoretical, but it can happen if the apic_ids on three
iterations of the loop are for example 1, KVM_IPI_CLUSTER_SIZE, 0.
Fixes: aaffcfd1e8 ("KVM: X86: Implement PV IPIs in linux guest")
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Message-Id: <1646814944-51801-1-git-send-email-lirongqing@baidu.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
FNAME(cmpxchg_gpte) is an inefficient mess. It is at least decent if it
can go through get_user_pages_fast(), but if it cannot then it tries to
use memremap(); that is not just terribly slow, it is also wrong because
it assumes that the VM_PFNMAP VMA is contiguous.
The right way to do it would be to do the same thing as
hva_to_pfn_remapped() does since commit add6a0cd1c ("KVM: MMU: try to
fix up page faults before giving up", 2016-07-05), using follow_pte()
and fixup_user_fault() to determine the correct address to use for
memremap(). To do this, one could for example extract hva_to_pfn()
for use outside virt/kvm/kvm_main.c. But really there is no reason to
do that either, because there is already a perfectly valid address to
do the cmpxchg() on, only it is a userspace address. That means doing
user_access_begin()/user_access_end() and writing the code in assembly
to handle exceptions correctly. Worse, the guest PTE can be 8-byte
even on i686 so there is the extra complication of using cmpxchg8b to
account for. But at least it is an efficient mess.
(Thanks to Linus for suggesting improvement on the inline assembly).
Reported-by: Qiuhao Li <qiuhao@sysec.org>
Reported-by: Gaoning Pan <pgn@zju.edu.cn>
Reported-by: Yongkang Jia <kangel@zju.edu.cn>
Reported-by: syzbot+6cde2282daa792c49ab8@syzkaller.appspotmail.com
Debugged-by: Tadeusz Struk <tadeusz.struk@linaro.org>
Tested-by: Maxim Levitsky <mlevitsk@redhat.com>
Cc: stable@vger.kernel.org
Fixes: bd53cb35a3 ("X86/KVM: Handle PFNs outside of kernel reach when touching GPTEs")
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When emulating exit from long mode, EFER_LMA is cleared with
vmx_set_efer(). This will already unset the VM_ENTRY_IA32E_MODE control
bit as requested by SDM, so there is no need to unset VM_ENTRY_IA32E_MODE
again in exit_lmode() explicitly. In case EFER isn't supported by
hardware, long mode isn't supported, so exit_lmode() cannot be reached.
Note that, thanks to the shadow controls mechanism, this change doesn't
eliminate vmread or vmwrite.
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Message-Id: <20220311102643.807507-3-zhenzhong.duan@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
vmx_set_efer() sets uret->data but, in fact if the value of uret->data
will be used vmx_setup_uret_msrs() will have rewritten it with the value
returned by update_transition_efer(). uret->data is consumed if and only
if uret->load_into_hardware is true, and vmx_setup_uret_msrs() takes care
of (a) updating uret->data before setting uret->load_into_hardware to true
(b) setting uret->load_into_hardware to false if uret->data isn't updated.
Opportunistically use "vmx" directly instead of redoing to_vmx().
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Message-Id: <20220311102643.807507-2-zhenzhong.duan@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
