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KVM: s390: fix handling of write errors in the tpi handler 

If the I/O interrupt could not be written to the guest provided
area (e.g. access exception), a program exception was injected into the
guest but "inti" wasn't freed, therefore resulting in a memory leak.

In addition, the I/O interrupt wasn't reinjected. Therefore the dequeued
interrupt is lost.

This patch fixes the problem while cleaning up the function and making the
cc and rc logic easier to handle.

Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Cc: stable@vger.kernel.org # 3.16+
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
This commit is contained in:
David Hildenbrand 2015-02-04 15:53:42 +01:00 committed by Christian Borntraeger
parent b75f4c9afa
commit 261520dcfc
1 changed files with 23 additions and 17 deletions
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40
arch/s390/kvm/priv.c
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@ -229,18 +229,19 @@ static int handle_tpi(struct kvm_vcpu *vcpu)
struct kvm_s390_interrupt_info *inti;
unsigned long len;
u32 tpi_data[3];
int cc, rc;
int rc;
u64 addr;
rc = 0;
addr = kvm_s390_get_base_disp_s(vcpu);
if (addr & 3)
return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
cc = 0;
inti = kvm_s390_get_io_int(vcpu->kvm, vcpu->arch.sie_block->gcr[6], 0);
if (!inti)
goto no_interrupt;
cc = 1;
if (!inti) {
kvm_s390_set_psw_cc(vcpu, 0);
return 0;
}
tpi_data[0] = inti->io.subchannel_id << 16 | inti->io.subchannel_nr;
tpi_data[1] = inti->io.io_int_parm;
tpi_data[2] = inti->io.io_int_word;
@ -251,30 +252,35 @@ static int handle_tpi(struct kvm_vcpu *vcpu)
*/
len = sizeof(tpi_data) - 4;
rc = write_guest(vcpu, addr, &tpi_data, len);
if (rc)
return kvm_s390_inject_prog_cond(vcpu, rc);
if (rc) {
rc = kvm_s390_inject_prog_cond(vcpu, rc);
goto reinject_interrupt;
}
} else {
/*
* Store the three-word I/O interruption code into
* the appropriate lowcore area.
*/
len = sizeof(tpi_data);
if (write_guest_lc(vcpu, __LC_SUBCHANNEL_ID, &tpi_data, len))
if (write_guest_lc(vcpu, __LC_SUBCHANNEL_ID, &tpi_data, len)) {
/* failed writes to the low core are not recoverable */
rc = -EFAULT;
goto reinject_interrupt;
}
}
/* irq was successfully handed to the guest */
kfree(inti);
kvm_s390_set_psw_cc(vcpu, 1);
return 0;
reinject_interrupt:
/*
* If we encounter a problem storing the interruption code, the
* instruction is suppressed from the guest's view: reinject the
* interrupt.
*/
if (!rc)
kfree(inti);
else
kvm_s390_reinject_io_int(vcpu->kvm, inti);
no_interrupt:
/* Set condition code and we're done. */
if (!rc)
kvm_s390_set_psw_cc(vcpu, cc);
kvm_s390_reinject_io_int(vcpu->kvm, inti);
/* don't set the cc, a pgm irq was injected or we drop to user space */
return rc ? -EFAULT : 0;
}