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[Qemu-devel] Re: SVM emulation: EVENTINJ marked valid when a pagefault h
From: |
Jan Kiszka |
Subject: |
[Qemu-devel] Re: SVM emulation: EVENTINJ marked valid when a pagefault happens while issuing a software interrupt |
Date: |
Fri, 28 May 2010 09:47:25 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
Roedel, Joerg wrote:
> On Thu, May 27, 2010 at 06:20:00PM -0400, Jan Kiszka wrote:
>> Erik van der Kouwe wrote:
>>> Problem is: I'm compiling in Linux and testing in MINIX. Testing on the
>>> real hardware would require a reboot everytime. Moreover, it might screw
>>> up my system if I make bad mistakes (the MINIX filesystem is easily
>>> corrupted).
>> Use Linux+KVM as host OS, it can also run VMMs as guests (aka nested
>> SVM). And you could even debug those guests just like when you would run
>> QEMU in emulation mode. In contrast to SVM emulation, nesting is fairly
>> stable AFAIK. And it is faster.
>
> At least it is more stable than any other nested-svm implementation I
> know of ;-)
> There are issues with kvmclock when you run kvm-on-kvm and you should
> not expect windows-based hypervisors to run without problems. Beside
> that, for running kvm-on-kvm and xen-on-kvm it is indeed fairly
> stable :-)
>
>>> Linux source tree (2.6.31-ubuntu), arch/x86/kvm/svm.c, end of function
>>> nested_svm_vmrun. Here event_inj and event_inj_err are copied from a
>>> different VMCB, effectively clearing the value set by the CPU. Maybe
>>> this isn't were I should have been looking though?
>
> The interesting part is in nested_svm_vmexit. There you have this piece
> of code:
>
> /*
> * If we emulate a VMRUN/#VMEXIT in the same host #vmexit cycle we
> have
> * to make sure that we do not lose injected events. So check
> event_inj
> * here and copy it to exit_int_info if it is valid.
> * Exit_int_info and event_inj can't be both valid because the case
> * below only happens on a VMRUN instruction intercept which has
> * no valid exit_int_info set.
> */
> if (vmcb->control.event_inj & SVM_EVTINJ_VALID) {
> struct vmcb_control_area *nc = &nested_vmcb->control;
>
> nc->exit_int_info = vmcb->control.event_inj;
> nc->exit_int_info_err = vmcb->control.event_inj_err;
> }
>
> and a few lines later:
>
> nested_vmcb->control.event_inj = 0;
> nested_vmcb->control.event_inj_err = 0;
>
> ... which takes care of this situation. The vmcb.eventinf field is _defined_
> to
> be zero on a #vmexit.
(Hmm, must have missed that line in the spec.)
In that case something like
diff --git a/target-i386/op_helper.c b/target-i386/op_helper.c
index dcbdfe7..caabdb4 100644
--- a/target-i386/op_helper.c
+++ b/target-i386/op_helper.c
@@ -1263,13 +1263,6 @@ void do_interrupt(int intno, int is_int, int error_code,
#endif
do_interrupt_real(intno, is_int, error_code, next_eip);
}
-
-#if !defined(CONFIG_USER_ONLY)
- if (env->hflags & HF_SVMI_MASK) {
- uint32_t event_inj = ldl_phys(env->vm_vmcb + offsetof(struct vmcb,
control.event_inj));
- stl_phys(env->vm_vmcb + offsetof(struct vmcb, control.event_inj),
event_inj & ~SVM_EVTINJ_VALID);
- }
-#endif
}
/* This should come from sysemu.h - if we could include it here... */
@@ -5388,6 +5381,7 @@ void helper_vmexit(uint32_t exit_code, uint64_t
exit_info_1)
ldl_phys(env->vm_vmcb + offsetof(struct vmcb,
control.event_inj)));
stl_phys(env->vm_vmcb + offsetof(struct vmcb, control.exit_int_info_err),
ldl_phys(env->vm_vmcb + offsetof(struct vmcb,
control.event_inj_err)));
+ stl_phys(env->vm_vmcb + offsetof(struct vmcb, control.event_inj), 0);
env->hflags2 &= ~HF2_GIF_MASK;
/* FIXME: Resets the current ASID register to zero (host ASID). */
should resolve the QEMU issue, right?
Jan
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- [Qemu-devel] Re: SVM emulation: EVENTINJ marked valid when a pagefault happens while issuing a software interrupt, (continued)
- [Qemu-devel] Re: SVM emulation: EVENTINJ marked valid when a pagefault happens while issuing a software interrupt, Jan Kiszka, 2010/05/27
- [Qemu-devel] Re: SVM emulation: EVENTINJ marked valid when a pagefault happens while issuing a software interrupt, Erik van der Kouwe, 2010/05/28
- [Qemu-devel] Re: SVM emulation: EVENTINJ marked valid when a pagefault happens while issuing a software interrupt, Jan Kiszka, 2010/05/28
- [Qemu-devel] Re: SVM emulation: EVENTINJ marked valid when a pagefault happens while issuing a software interrupt, Roedel, Joerg, 2010/05/28
- Re: [Qemu-devel] Re: SVM emulation: EVENTINJ marked valid when a pagefault happens while issuing a software interrupt, Jamie Lokier, 2010/05/28
- Re: [Qemu-devel] Re: SVM emulation: EVENTINJ marked valid when a pagefault happens while issuing a software interrupt, Erik van der Kouwe, 2010/05/28
- Re: [Qemu-devel] Re: SVM emulation: EVENTINJ marked valid when a pagefault happens while issuing a software interrupt, Roedel, Joerg, 2010/05/28
- Re: [Qemu-devel] Re: SVM emulation: EVENTINJ marked valid when a pagefault happens while issuing a software interrupt, Erik van der Kouwe, 2010/05/28
- Re: [Qemu-devel] Re: SVM emulation: EVENTINJ marked valid when a pagefault happens while issuing a software interrupt, Roedel, Joerg, 2010/05/28
- [Qemu-devel] Re: SVM emulation: EVENTINJ marked valid when a pagefault happens while issuing a software interrupt, Roedel, Joerg, 2010/05/28
- [Qemu-devel] Re: SVM emulation: EVENTINJ marked valid when a pagefault happens while issuing a software interrupt,
Jan Kiszka <=
[Qemu-devel] Re: SVM emulation: EVENTINJ marked valid when a pagefault happens while issuing a software interrupt, Roedel, Joerg, 2010/05/28