On 10/21/2020 6:01 AM, Sean Christopherson wrote:
On Mon, Oct 12, 2020 at 11:35:41AM +0800, Chenyi Qiang wrote:
From: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Convert vcpu_vmx.exit_reason from a u32 to a union (of size u32). The
full VM_EXIT_REASON field is comprised of a 16-bit basic exit reason in
bits 15:0, and single-bit modifiers in bits 31:16.
Historically, KVM has only had to worry about handling the "failed
VM-Entry" modifier, which could only be set in very specific flows and
required dedicated handling. I.e. manually stripping the FAILED_VMENTRY
bit was a somewhat viable approach. But even with only a single bit to
worry about, KVM has had several bugs related to comparing a basic exit
reason against the full exit reason store in vcpu_vmx.
Upcoming Intel features, e.g. SGX, will add new modifier bits that can
be set on more or less any VM-Exit, as opposed to the significantly more
restricted FAILED_VMENTRY, i.e. correctly handling everything in one-off
flows isn't scalable. Tracking exit reason in a union forces code to
explicitly choose between consuming the full exit reason and the basic
exit, and is a convenient way to document and access the modifiers.
No functional change intended.
Cc: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
This needs your SOB since you are involved in the handling of the patch.
Sorry for the late response, my mailbox encountered some issues...
Will add the SOB here.
