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Linux kernel source tree
0a94b20424
Drop the fastpath VM-Exit requirement that KVM can use the hypervisor timer to emulate the APIC timer in TSC deadline mode. I.e. unconditionally handle MSR_IA32_TSC_DEADLINE WRMSRs in the fastpath. Restricting the fastpath to *maybe* using the VMX preemption timer is ineffective and unnecessary. If the requested deadline can't be programmed into the VMX preemption timer, KVM will fall back to hrtimers, i.e. the restriction is ineffective as far as preventing any kind of worst case scenario. But guarding against a worst case scenario is completely unnecessary as the "slow" path, start_sw_tscdeadline() => hrtimer_start(), explicitly disables IRQs. In fact, the worst case scenario is when KVM thinks it can use the VMX preemption timer, as KVM will eat the overhead of calling into vmx_set_hv_timer() and falling back to hrtimers. Opportunistically limit kvm_can_use_hv_timer() to lapic.c as the fastpath code was the only external user. Stating the obvious, this allows handling MSR_IA32_TSC_DEADLINE writes in the fastpath on AMD CPUs. Link: https://lore.kernel.org/r/20250805190526.1453366-6-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com> |
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .clippy.toml | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .pylintrc | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| 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 reStructuredText 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.