[PATCH AUTOSEL 5.14 29/40] swiotlb-xen: ensure to issue well-formed XENMEM_exchange requests

[Sasha Levin <sashal@xxxxxxxxxx>]

From: Jan Beulich <jbeulich@xxxxxxxx>

[ Upstream commit 9074c79b62b6e0d91d7f716c6e4e9968eaf9e043 ]

While the hypervisor hasn't been enforcing this, we would still better
avoid issuing requests with GFNs not aligned to the requested order.
Instead of altering the value also in the call to panic(), drop it
there for being static and hence easy to determine without being part
of the panic message.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Link: https://lore.kernel.org/r/7b3998e3-1233-4e5a-89ec-d740e77eb166@xxxxxxxx
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/xen/swiotlb-xen.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index dbb18dc956f3..de4f55154d49 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -232,10 +232,11 @@ void __init xen_swiotlb_init_early(void)
        /*
         * Get IO TLB memory from any location.
         */
-       start = memblock_alloc(PAGE_ALIGN(bytes), PAGE_SIZE);
+       start = memblock_alloc(PAGE_ALIGN(bytes),
+                              IO_TLB_SEGSIZE << IO_TLB_SHIFT);
        if (!start)
-               panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
-                     __func__, PAGE_ALIGN(bytes), PAGE_SIZE);
+               panic("%s: Failed to allocate %lu bytes\n",
+                     __func__, PAGE_ALIGN(bytes));
 
        /*
         * And replace that memory with pages under 4GB.
-- 
2.33.0