Sean Christopherson 6c593b5276 KVM: x86: Hoist nested event checks above event injection logic
Perform nested event checks before re-injecting exceptions/events into
L2.  If a pending exception causes VM-Exit to L1, re-injecting events
into vmcs02 is premature and wasted effort.  Take care to ensure events
that need to be re-injected are still re-injected if checking for nested
events "fails", i.e. if KVM needs to force an immediate entry+exit to
complete the to-be-re-injecteed event.

Keep the "can_inject" logic the same for now; it too can be pushed below
the nested checks, but is a slightly riskier change (see past bugs about
events not being properly purged on nested VM-Exit).

Add and/or modify comments to better document the various interactions.
Of note is the comment regarding "blocking" previously injected NMIs and
IRQs if an exception is pending.  The old comment isn't wrong strictly
speaking, but it failed to capture the reason why the logic even exists.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Link: https://lore.kernel.org/r/20220830231614.3580124-18-seanjc@google.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-09-26 12:03:09 -04:00
2022-08-12 09:07:33 -07:00
2022-09-26 12:02:27 -04:00
2022-08-14 15:50:18 -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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