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Sean Christopherson
712494de96
Fully emulate a guest TLB flush on nested VM-Enter which changes vpid12,
i.e. L2's VPID, instead of simply doing INVVPID to flush real hardware's
TLB entries for vpid02. From L1's perspective, changing L2's VPID is
effectively a TLB flush unless "hardware" has previously cached entries
for the new vpid12. Because KVM tracks only a single vpid12, KVM doesn't
know if the new vpid12 has been used in the past and so must treat it as
a brand new, never been used VPID, i.e. must assume that the new vpid12
represents a TLB flush from L1's perspective.
For example, if L1 and L2 share a CR3, the first VM-Enter to L2 (with a
VPID) is effectively a TLB flush as hardware/KVM has never seen vpid12
and thus can't have cached entries in the TLB for vpid12.
Reported-by: Lai Jiangshan <jiangshanlai+lkml@gmail.com>
Fixes: 5c614b3583 ("KVM: nVMX: nested VPID emulation")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211125014944.536398-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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.