mirror of
https://github.com/hardkernel/linux.git
synced 2026-06-05 18:41:58 +09:00
fa9089949d
[ Upstream commitf66af9f222] In emulation of writing to cr8, one of the lowest four bits in TPR[3:0] is kept. According to Intel SDM 10.8.6.1(baremetal scenario): "APIC.TPR[bits 7:4] = CR8[bits 3:0], APIC.TPR[bits 3:0] = 0"; and SDM 28.3(use TPR shadow): "MOV to CR8. The instruction stores bits 3:0 of its source operand into bits 7:4 of VTPR; the remainder of VTPR (bits 3:0 and bits 31:8) are cleared."; and AMD's APM 16.6.4: "Task Priority Sub-class (TPS)-Bits 3 : 0. The TPS field indicates the current sub-priority to be used when arbitrating lowest-priority messages. This field is written with zero when TPR is written using the architectural CR8 register."; so in KVM emulated scenario, clear TPR[3:0] to make a consistent behavior as in other scenarios. This doesn't impact evaluation and delivery of pending virtual interrupts because processor does not use the processor-priority sub-class to determine which interrupts to delivery and which to inhibit. Sub-class is used by hardware to arbitrate lowest priority interrupts, but KVM just does a round-robin style delivery. Fixes:b93463aa59("KVM: Accelerated apic support") Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com> Reviewed-by: Sean Christopherson <seanjc@google.com> Message-Id: <20220210094506.20181-1-zhenzhong.duan@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
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.