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KVM: SVM: Move INTR vmexit out of atomic code 

The nested SVM code emulates a #vmexit caused by a request
to open the irq window right in the request function. This
is a bug because the request function runs with preemption
and interrupts disabled but the #vmexit emulation might
sleep. This can cause a schedule()-while-atomic bug and is
fixed with this patch.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
hifive-unleashed-5.1
Joerg Roedel 2009-10-09 16:08:26 +02:00 committed by Avi Kivity
parent 8d23c46624
commit cd3ff653ae
1 changed files with 25 additions and 1 deletions
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26
arch/x86/kvm/svm.c
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@ -85,6 +85,9 @@ struct nested_state {
/* gpa pointers to the real vectors */
u64 vmcb_msrpm;
/* A VMEXIT is required but not yet emulated */
bool exit_required;
/* cache for intercepts of the guest */
u16 intercept_cr_read;
u16 intercept_cr_write;
@ -1379,7 +1382,14 @@ static inline int nested_svm_intr(struct vcpu_svm *svm)
svm->vmcb->control.exit_code = SVM_EXIT_INTR;
if (nested_svm_exit_handled(svm)) {
if (svm->nested.intercept & 1ULL) {
/*
* The #vmexit can't be emulated here directly because this
* code path runs with irqs and preemtion disabled. A
* #vmexit emulation might sleep. Only signal request for
* the #vmexit here.
*/
svm->nested.exit_required = true;
nsvm_printk("VMexit -> INTR\n");
return 1;
}
@ -2340,6 +2350,13 @@ static int handle_exit(struct kvm_vcpu *vcpu)
trace_kvm_exit(exit_code, svm->vmcb->save.rip);
if (unlikely(svm->nested.exit_required)) {
nested_svm_vmexit(svm);
svm->nested.exit_required = false;
return 1;
}
if (is_nested(svm)) {
int vmexit;
@ -2615,6 +2632,13 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)
u16 gs_selector;
u16 ldt_selector;
/*
* A vmexit emulation is required before the vcpu can be executed
* again.
*/
if (unlikely(svm->nested.exit_required))
return;
svm->vmcb->save.rax = vcpu->arch.regs[VCPU_REGS_RAX];
svm->vmcb->save.rsp = vcpu->arch.regs[VCPU_REGS_RSP];
svm->vmcb->save.rip = vcpu->arch.regs[VCPU_REGS_RIP];