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[Qemu-devel] [Bug 720657] Re: SVM intercept for VINTR exits too early
From: |
Thomas Huth |
Subject: |
[Qemu-devel] [Bug 720657] Re: SVM intercept for VINTR exits too early |
Date: |
Wed, 15 Mar 2017 08:08:12 -0000 |
Triaging old bug tickets ... can you still reproduce this problem with
the latest version of QEMU?
** Changed in: qemu
Status: New => Incomplete
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https://bugs.launchpad.net/bugs/720657
Title:
SVM intercept for VINTR exits too early
Status in QEMU:
Incomplete
Bug description:
The following happens with QEMU-0.14-rc2. QEMU-0.13 did not have this
problem.
A guest operating system running inside an SVM VM contains the following code
sequence:
c000002b: fb sti
c000002c: 0f 35 sysexit
The following is a list of exits that occur at guest RIP 0xc000002c
(other exits omitted for clarity):
exit=0x60 int_shadow=0x1 int_control=0x1000000 inj=0x600000000 rip=0xc000002c
entry: int_shadow=0x1 int_control=0x1000000 inj=0x600000000
(exit due to physical interrupt, correctly reports STI blocking, entry
does not inject anything)
exit=0x60 int_shadow=0x1 int_control=0x1000000 inj=0x600000000 rip=0xc000002c
entry: int_shadow=0x1 int_control=0x1100100 inj=0x600000000
(exit due to physical interrupt, correctly reports STI blocking, entry
pends a VINTR to cause a VM exit when interrupt window opens. VINTR is
being intercepted by the hypervisor.)
exit=0x64 int_shadow=0x0 int_control=0x1100100 inj=0x600000000 rip=0xc000002c
entry: int_shadow=0x0 int_control=0x1000000 inj=0x6800000a0
(exit due to VINTR. At this point STI blocking is still effective -
though not reported. Actually, the VINTR exit should occur AFTER the
SYSEXIT instruction, not after STI. Due to this bug, the hypervisor
injects vector 0xa0 into an interrupt shadow, and things break).
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