On 08.01.19 11:34, Cornelia Huck wrote:
On Mon, 7 Jan 2019 18:38:02 +0100
Michael Mueller <mimu@xxxxxxxxxxxxx> wrote:
On 04.01.19 14:19, Cornelia Huck wrote:
On Wed, 2 Jan 2019 18:29:00 +0100
Pierre Morel <pmorel@xxxxxxxxxxxxx> wrote:
On 19/12/2018 20:17, Michael Mueller wrote:
Add the IAM (Interruption Alert Mask) to the architecture specific
kvm struct. This mask in the GISA is used to define for which ISC
a GIB alert can be issued.
The functions kvm_s390_gisc_register() and kvm_s390_gisc_unregister()
are used to (un)register a GISC (guest ISC) with a virtual machine and
its GISA.
Upon successful completion, kvm_s390_gisc_register() returns the
ISC to be used for GIB alert interruptions. A negative return code
indicates an error during registration.
Theses functions will be used by other adapter types like AP and PCI to
request pass-through interruption support.
Signed-off-by: Michael Mueller <mimu@xxxxxxxxxxxxx>
---
arch/s390/include/asm/kvm_host.h | 9 ++++++
arch/s390/kvm/interrupt.c | 66 ++++++++++++++++++++++++++++++++++++++++
2 files changed, 75 insertions(+)
+int kvm_s390_gisc_register(struct kvm *kvm, u32 gisc)
+{
+ if (!kvm->arch.gib_in_use)
+ return -ENODEV;
+ if (gisc > MAX_ISC)
+ return -ERANGE;
+
+ spin_lock(&kvm->arch.iam_ref_lock);
+ if (kvm->arch.iam_ref_count[gisc] == 0)
+ kvm->arch.iam |= 0x80 >> gisc;
+ kvm->arch.iam_ref_count[gisc]++;
+ if (kvm->arch.iam_ref_count[gisc] == 1)
+ set_iam(kvm->arch.gisa, kvm->arch.iam);
testing the set_iam return value?
Even it should be fine if the caller works correctly, this is done
before GISA is ever used.
There is a rc but a check here is not required.
There are three cases:
a) This is the first ISC that gets registered, then the GISA is
not in use and IAM is set in the GISA.
b) A second ISC gets registered and the GISA is *not* in the
alert list. Then the IAM is set here as well.
c) A second ISC gets registered and the GISA is in the
alert list. Then the IAM is intentionally not set here
by set_iam(). It will be restored by get_ipm() with
the new IAM value by the gib alert processing code.
My feeling is that checking the return code is a good idea, even if it
Should Never Fail(tm).
+ spin_unlock(&kvm->arch.iam_ref_lock);
+
+ return gib->nisc;
+}
+EXPORT_SYMBOL_GPL(kvm_s390_gisc_register);
+
+int kvm_s390_gisc_unregister(struct kvm *kvm, u32 gisc)
+{
+ int rc = 0;
+
+ if (!kvm->arch.gib_in_use)
+ return -ENODEV;
+ if (gisc > MAX_ISC)
+ return -ERANGE;
+
+ spin_lock(&kvm->arch.iam_ref_lock);
+ if (kvm->arch.iam_ref_count[gisc] == 0) {
+ rc = -EINVAL;
+ goto out;
+ }
+ kvm->arch.iam_ref_count[gisc]--;
+ if (kvm->arch.iam_ref_count[gisc] == 0) {
+ kvm->arch.iam &= ~(0x80 >> gisc);
+ set_iam(kvm->arch.gisa, kvm->arch.iam);
Any chance of this function failing here? If yes, would there be any
implications?
It is the same here.
I'm not sure that I follow: This is the reverse operation
(unregistering the gisc). Can we rely on get_ipm() to do any fixup
later? Is that a problem for the caller?
Apologies if I sound confused (well, that's because I probably am);
this is hard to review without access to the hardware specification.
I think nothing will happen because the AP CLR IRQ call (Pierre?)
has already taken offline the last AP device.
+ }
+out:
+ spin_unlock(&kvm->arch.iam_ref_lock);
+
+ return rc;
+}
+EXPORT_SYMBOL_GPL(kvm_s390_gisc_unregister);
+
void kvm_s390_gib_destroy(void)
{
if (!gib)
