[PATCH 5.3 078/105] KVM: PPC: Book3S HV: XIVE: Set kvm->arch.xive when VPs are allocated

Greg Kroah-Hartman
2019-12-11T15:15:25Z

From: Greg Kurz <groug@kaod.org>

commit e7d71c943040c23f2fd042033d319f56e84f845b upstream.

If we cannot allocate the XIVE VPs in OPAL, the creation of a XIVE or
XICS-on-XIVE device is aborted as expected, but we leave kvm->arch.xive
set forever since the release method isn't called in this case. Any
subsequent tentative to create a XIVE or XICS-on-XIVE for this VM will
thus always fail (DoS). This is a problem for QEMU since it destroys
and re-creates these devices when the VM is reset: the VM would be
restricted to using the much slower emulated XIVE or XICS forever.

As an alternative to adding rollback, do not assign kvm->arch.xive before
making sure the XIVE VPs are allocated in OPAL.

Cc: stable@vger.kernel.org # v5.2
Fixes: 5422e95103cf ("KVM: PPC: Book3S HV: XIVE: Replace the 'destroy' method by a 'release' method")
Signed-off-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/powerpc/kvm/book3s_xive.c | 11 +++++------
arch/powerpc/kvm/book3s_xive_native.c | 2 +-
2 files changed, 6 insertions(+), 7 deletions(-)

--- a/arch/powerpc/kvm/book3s_xive.c
+++ b/arch/powerpc/kvm/book3s_xive.c
@@ -2005,6 +2005,10 @@ static int kvmppc_xive_create(struct kvm

pr_devel("Creating xive for partition\n");

+ /* Already there ? */
+ if (kvm->arch.xive)
+ return -EEXIST;
+
xive = kvmppc_xive_get_device(kvm, type);
if (!xive)
return -ENOMEM;
@@ -2014,12 +2018,6 @@ static int kvmppc_xive_create(struct kvm
xive->kvm = kvm;
mutex_init(&xive->lock);

- /* Already there ? */
- if (kvm->arch.xive)
- ret = -EEXIST;
- else
- kvm->arch.xive = xive;
-
/* We use the default queue size set by the host */
xive->q_order = xive_native_default_eq_shift();
if (xive->q_order < PAGE_SHIFT)
@@ -2039,6 +2037,7 @@ static int kvmppc_xive_create(struct kvm
if (ret)
return ret;

+ kvm->arch.xive = xive;
return 0;
}

--- a/arch/powerpc/kvm/book3s_xive_native.c
+++ b/arch/powerpc/kvm/book3s_xive_native.c
@@ -1095,7 +1095,6 @@ static int kvmppc_xive_native_create(str
dev->private = xive;
xive->dev = dev;
xive->kvm = kvm;
- kvm->arch.xive = xive;
mutex_init(&xive->mapping_lock);
mutex_init(&xive->lock);

@@ -1116,6 +1115,7 @@ static int kvmppc_xive_native_create(str
if (ret)
return ret;

+ kvm->arch.xive = xive;
return 0;
}