From: Jork Loeser <jloe...@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 <jloe...@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

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