The vmclock device addresses the problem of live migration with
precision clocks. The tolerances of a hardware counter (e.g. TSC) are
typically around ±50PPM. A guest will use NTP/PTP/PPS to discipline that
counter against an external source of 'real' time, and track the precise
frequency of the counter as it changes with environmental conditions.
When a guest is live migrated, anything it knows about the frequency of
the underlying counter becomes invalid. It may move from a host where
the counter running at -50PPM of its nominal frequency, to a host where
it runs at +50PPM. There will also be a step change in the value of the
counter, as the correctness of its absolute value at migration is
limited by the accuracy of the source and destination host's time
synchronization.
The device exposes a shared memory region to guests, which can be mapped
all the way to userspace. In the first phase, this merely advertises a
'disruption_marker', which indicates that the guest should throw away any
NTP synchronization it thinks it has, and start again.
Because the region can be exposed all the way to userspace, applications
can still use time from a fast vDSO 'system call', and check the
disruption marker to be sure that their timestamp is indeed truthful.
The structure also allows for the precise time, as known by the host, to
be exposed directly to guests so that they don't have to wait for NTP to
resync from scratch.
The values and fields are based on the nascent virtio-rtc specification,
and the intent is that a version (hopefully precisely this version) of
this structure will be included as an optional part of that spec. In the
meantime, a simple ACPI device along the lines of VMGENID is perfectly
sufficient and is compatible with what's being shipped in certain
commercial hypervisors.
Linux guest support was merged into the 6.13-rc1 kernel:
https://git.kernel.org/torvalds/c/205032724226
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
Message-Id: <07fd5e2f529098ad4d7cab1423fe9f4a03a9cc14.camel@infradead.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
since 6.11, unistd.h includes header file unistd_64.h directly on
some platforms, here add unistd_64.h on these platforms. Affected
platforms are ARM64, LoongArch64 and Riscv. Otherwise there will
be compiling error such as:
linux-headers/asm/unistd.h:3:10: fatal error: asm/unistd_64.h: No such file or directory
#include <asm/unistd_64.h>
Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Acked-by: Song Gao <gaosong@loongson.cn>
Message-Id: <20241028023809.1554405-2-maobibo@loongson.cn>
Signed-off-by: Song Gao <gaosong@loongson.cn>
Right now QEMU is importing arch/x86/include/uapi/asm/kvm_para.h
because it includes definitions for kvmclock and for KVM CPUID
bits. However, other definitions for KVM hypercall values and return
codes are included in include/uapi/linux/kvm_para.h and they will be
used by SEV-SNP.
To ensure that it is possible to include both <linux/kvm_para.h> and
"standard-headers/asm-x86/kvm_para.h" without conflicts, provide
linux/kvm_para.h as a portable header too, and forward linux-headers/
files to those in include/standard-headers. Note that <linux/kvm_para.h>
will include architecture-specific definitions as well, but
"standard-headers/linux/kvm_para.h" will not because it can be used in
architecture-independent files.
This could easily be extended to other architectures, but right now
they do not need any symbol in their specific kvm_para.h files.
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Linux has <misc/pvpanic.h>, not <linux/pvpanic.h>. Use the same
directory for QEMU's include/standard-headers/ copy.
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Afer commit 3efc75ad9d ("scripts/update-linux-headers.sh: Remove
temporary directory inbetween", 2024-05-29), updating linux-headers/
results in errors such as
cp: cannot stat '/tmp/tmp.1A1Eejh1UE/headers/include/asm/bitsperlong.h': No such file or directory
because Loongarch does not have an asm/bitsperlong.h file and uses the
generic version. Before commit 3efc75ad9d, the missing file would
incorrectly cause stale files to be included in linux-headers/. The files
were never committed to qemu.git, but were wrong nevertheless. The build
would just use the system version of the files, which is opposite to
the idea of importing Linux header files into QEMU's tree.
Create forwarding headers, resembling the ones that are generated during a
kernel build by scripts/Makefile.asm-generic, if a file is only installed
under include/asm-generic/.
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When running the update-linx-headers.sh script, it currently fails with:
scripts/update-linux-headers.sh: line 73: .../qemu/standard-headers/asm-x86/setup_data.h: No such file or directory
The "include" folder is obviously missing here - no clue how this could
have worked before?
Fixes: 66210a1a30 ("scripts/update-linux-headers: Add setup_data.h to import list")
Message-ID: <20240527060126.12578-1-thuth@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
We are reusing the same temporary directory for installing the headers
of all targets, so there could be stale files here when switching from
one target to another. Make sure to delete the folder before installing
a new set of target headers into it.
Message-ID: <20240527060243.12647-1-thuth@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Running "install_headers" in the Linux source tree is fairly
unfriendly as out-of-tree builds will start complaining about the
kernel source being non-pristine. As we have a temporary directory for
the install we should also do the build step here. So now we have:
$tmpdir/
$blddir/
$hdrdir/
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240514174253.694591-3-alex.bennee@linaro.org>
Data structures like struct setup_data have been moved to a separate
setup_data.h header which bootparam.h relies on. Add setup_data.h to
the cp_portable() list and sync it along with the other header files.
Note that currently struct setup_data is stripped away as part of
generating bootparam.h, but that handling is no currently needed for
setup_data.h since it doesn't pull in many external
headers/dependencies. However, QEMU currently redefines struct
setup_data in hw/i386/x86.c, so that will need to be removed as part of
any header update that pulls in the new setup_data.h to avoid build
bisect breakage.
Because <asm/setup_data.h> is the first architecture specific #include
in include/standard-headers/, add a new sed substitution to rewrite
asm/ include to the standard-headers/asm-* subdirectory for the current
architecture.
And while at it, remove asm-generic/kvm_para.h from the list of
allowed includes: it does not have a matching substitution, and therefore
it would not be possible to use it on non-Linux systems where there is
no /usr/include/asm-generic/ directory.
Signed-off-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add <linux/memfd.h>, used by hw/display/virtio-gpu-udmabuf.c
Add <linux/nvme_ioctl.h>, used by qga/commands-posix.c
Add <linux/const.h> used by kvm-all.c, which requires
the _BITUL() macro definition to be available.
Without these, QEMU will not compile on Debian 10 systems.
Signed-off-by: David 'Digit' Turner <digit@google.com>
Message-Id: <20230405172109.3081788-3-digit@google.com>
[Add <linux/stddef.h> for __DECLARE_FLEX_ARRAY. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
If you don't know it, it's hard to figure out the difference between
the linux-headers folder and the include/standard-headers folder.
So let's add a short explanation to clarify the difference.
Suggested-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
