Maxim Levitsky 5d1ec45652 KVM: nSVM: Raise event on nested VM exit if L1 doesn't intercept IRQs
If L1 doesn't intercept interrupts, then KVM will use vmcb02's V_IRQ
to detect an interrupt window for L1 IRQs.  On a subsequent nested
VM-Exit, KVM might need to copy the current V_IRQ from vmcb02 to vmcb01
to continue waiting for an interrupt window, i.e. if there is still a
pending IRQ for L1.

Raise KVM_REQ_EVENT on nested exit if L1 isn't intercepting IRQs to ensure
that KVM will re-enable interrupt window detection if needed.

Note that this is a theoretical bug because KVM already raises
KVM_REQ_EVENT on each nested VM exit, because the nested VM exit resets
RFLAGS and kvm_set_rflags() raises the KVM_REQ_EVENT unconditionally.

Explicitly raise KVM_REQ_EVENT for the interrupt window case to avoid
having an unnecessary dependency on kvm_set_rflags(), and to document
the scenario.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
[santosh: reworded description as per Sean's v2 comment]
Signed-off-by: Santosh Shukla <Santosh.Shukla@amd.com>
Link: https://lore.kernel.org/r/20230227084016.3368-4-santosh.shukla@amd.com
[sean: further massage changelog and comment]
Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-03-22 12:33:58 -07:00
2023-03-05 10:49:37 -08:00
2022-09-28 09:02:20 +02:00
2023-03-12 16:36:44 -07:00

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.
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