[PATCH 2/4] Hyper-V vPCI: Use page allocation for hbus structure

Jork Loeser
2017-05-18T19:16:11Z

From: Jork Loeser <jloeser@microsoft.com>

The hv_pcibus_device structure contains an in-memory hypercall argument
that must not cross a page boundary. Allocate the structure as a page
to ensure that.

Signed-off-by: Jork Loeser <jloeser@microsoft.com>
---
drivers/pci/host/pci-hyperv.c | 12 +++++++++---
1 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
index 7bebdc6..aa836e9 100644
--- a/drivers/pci/host/pci-hyperv.c
+++ b/drivers/pci/host/pci-hyperv.c
@@ -2204,7 +2204,13 @@ static int hv_pci_probe(struct hv_device *hdev,
struct hv_pcibus_device *hbus;
int ret;

- hbus = kzalloc(sizeof(*hbus), GFP_KERNEL);
+ /*
+ * hv_pcibus_device contains the hypercall arguments for retargeting in
+ * hv_irq_unmask(). Those must not cross a page boundary.
+ */
+ BUILD_BUG_ON(sizeof(*hbus) > PAGE_SIZE);
+
+ hbus = (struct hv_pcibus_device *)get_zeroed_page(GFP_KERNEL);
if (!hbus)
return -ENOMEM;
hbus->state = hv_pcibus_init;
@@ -2308,7 +2314,7 @@ static int hv_pci_probe(struct hv_device *hdev,
close:
vmbus_close(hdev->channel);
free_bus:
- kfree(hbus);
+ free_page((unsigned long)hbus);
return ret;
}

@@ -2386,7 +2392,7 @@ static int hv_pci_remove(struct hv_device *hdev)
irq_domain_free_fwnode(hbus->sysdata.fwnode);
put_hvpcibus(hbus);
wait_for_completion(&hbus->remove_event);
- kfree(hbus);
+ free_page((unsigned long)hbus);
return 0;
}

--
1.7.1