From: Metin Kaya <metikaya@xxxxxxxxxx>
This patch introduces compat version of struct sched_poll for
SCHEDOP_poll sub-operation of sched_op hypercall, reads correct amount
of data (16 bytes in 32-bit case, 24 bytes otherwise) by using new
compat_sched_poll struct, copies it to sched_poll properly, and lets
rest of the code run as is.
Signed-off-by: Metin Kaya <metikaya@xxxxxxxxxx>
Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
---
v2 (Metin): Updated a comment and added a new one.
v3 (dwmw2): Take the simple path on 32-bit host, minor cosmetics.
I would have liked a self-test, but that requires actually invoking the
hypercall from 32-bit mode and AFAICT the KVM self-tests don't support
that, so it's probably not reasonable to demand that Metin implement it
just to test this relatively simple case.
arch/x86/kvm/xen.c | 33 +++++++++++++++++++++++++++++----
arch/x86/kvm/xen.h | 7 +++++++
2 files changed, 36 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
index c3180fe9d918..f1f6d849ed50 100644
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -1157,20 +1157,45 @@ static bool kvm_xen_schedop_poll(struct kvm_vcpu *vcpu, bool longmode,
evtchn_port_t port, *ports;
gpa_t gpa;
- if (!longmode || !lapic_in_kernel(vcpu) ||
+ if (!lapic_in_kernel(vcpu) ||
!(vcpu->kvm->arch.xen_hvm_config.flags & KVM_XEN_HVM_CONFIG_EVTCHN_SEND))
return false;
idx = srcu_read_lock(&vcpu->kvm->srcu);
gpa = kvm_mmu_gva_to_gpa_system(vcpu, param, NULL);
srcu_read_unlock(&vcpu->kvm->srcu, idx);
-
- if (!gpa || kvm_vcpu_read_guest(vcpu, gpa, &sched_poll,
- sizeof(sched_poll))) {
+ if (!gpa) {
*r = -EFAULT;
return true;
}
+ if (IS_ENABLED(CONFIG_64BIT) && !longmode) {
+ struct compat_sched_poll sp32;
+
+ /* Sanity check that the compat struct definition is correct */
+ BUILD_BUG_ON(sizeof(sp32) != 16);
+
+ if (kvm_vcpu_read_guest(vcpu, gpa, &sp32, sizeof(sp32))) {
+ *r = -EFAULT;
+ return true;
+ }
+
+ /*
+ * This is a 32-bit pointer to an array of evtchn_port_t which
+ * are uint32_t, so once it's converted no further compat
+ * handling is needed.
+ */
+ sched_poll.ports = (void *)(unsigned long)(sp32.ports);
+ sched_poll.nr_ports = sp32.nr_ports;
+ sched_poll.timeout = sp32.timeout;
+ } else {
+ if (kvm_vcpu_read_guest(vcpu, gpa, &sched_poll,
+ sizeof(sched_poll))) {
+ *r = -EFAULT;
+ return true;
+ }
+ }
+
if (unlikely(sched_poll.nr_ports > 1)) {
/* Xen (unofficially) limits number of pollers to 128 */
if (sched_poll.nr_ports > 128) {
diff --git a/arch/x86/kvm/xen.h b/arch/x86/kvm/xen.h
index 8503d2c6891e..ea33d80a0c51 100644
--- a/arch/x86/kvm/xen.h
+++ b/arch/x86/kvm/xen.h
@@ -207,4 +207,11 @@ struct compat_vcpu_runstate_info {
uint64_t time[4];
} __attribute__((packed));
+struct compat_sched_poll {
+ /* This is actually a guest virtual address which points to ports. */
+ uint32_t ports;
+ unsigned int nr_ports;
+ uint64_t timeout;
+};
+
#endif /* __ARCH_X86_KVM_XEN_H__ */
--
2.35.3
Attachment:
smime.p7s
Description: S/MIME cryptographic signature
