[PATCH v2 2/2] drivers/char: Use sub-page ro API to make just xhci dbc cap RO

[Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>]

Not the whole page, which may contain other registers too. In fact
on Tiger Lake and newer (at least), this page do contain other registers
that Linux tries to use. And with share=yes, a domU would use them too.
Without this patch, PV dom0 would fail to initialize the controller,
while HVM would be killed on EPT violation.

Signed-off-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
---
Changes in v2:
 - adjust for simplified subpage_mmio_ro_add() API
---
 xen/drivers/char/xhci-dbc.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/xen/drivers/char/xhci-dbc.c b/xen/drivers/char/xhci-dbc.c
index 60b781f87202..8e368364c933 100644
--- a/xen/drivers/char/xhci-dbc.c
+++ b/xen/drivers/char/xhci-dbc.c
@@ -1221,14 +1221,12 @@ static void __init cf_check 
dbc_uart_init_postirq(struct serial_port *port)
      * Linux's XHCI driver (as of 5.18) works without writting to the whole
      * page, so keep it simple.
      */
-    if ( rangeset_add_range(mmio_ro_ranges,
-                PFN_DOWN((uart->dbc.bar_val & PCI_BASE_ADDRESS_MEM_MASK) +
-                         uart->dbc.xhc_dbc_offset),
-                PFN_UP((uart->dbc.bar_val & PCI_BASE_ADDRESS_MEM_MASK) +
-                       uart->dbc.xhc_dbc_offset +
-                sizeof(*uart->dbc.dbc_reg)) - 1) )
-        printk(XENLOG_INFO
-               "Error while adding MMIO range of device to mmio_ro_ranges\n");
+    if ( subpage_mmio_ro_add(
+            (uart->dbc.bar_val & PCI_BASE_ADDRESS_MEM_MASK) +
+             uart->dbc.xhc_dbc_offset,
+            sizeof(*uart->dbc.dbc_reg)) )
+        printk(XENLOG_WARNING
+               "Error while marking MMIO range of XHCI console as R/O\n");
 #endif
 }
 
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git-series 0.9.1