[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [PATCH v4 2/2] drivers/char: Use sub-page ro API to make just xhci dbc cap RO
Not the whole page, which may contain other registers too. The XHCI specification describes DbC as designed to be controlled by a different driver, but does not mandate placing registers on a separate page. 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. With `share=yes`, this patch gives domU more access to the emulator (although a HVM with any emulated device already has plenty of it). This configuration is already documented as unsafe with untrusted guests and not security supported. Signed-off-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx> --- Changes in v4: - restore mmio_ro_ranges in the fallback case - set XHCI_SHARE_NONE in the fallback case Changes in v3: - indentation fix - remove stale comment - fallback to pci_ro_device() if subpage_mmio_ro_add() fails - extend commit message Changes in v2: - adjust for simplified subpage_mmio_ro_add() API --- xen/drivers/char/xhci-dbc.c | 36 ++++++++++++++++++++++-------------- 1 file changed, 22 insertions(+), 14 deletions(-) diff --git a/xen/drivers/char/xhci-dbc.c b/xen/drivers/char/xhci-dbc.c index 8e2037f1a5f7..c45e4b6825cc 100644 --- a/xen/drivers/char/xhci-dbc.c +++ b/xen/drivers/char/xhci-dbc.c @@ -1216,20 +1216,28 @@ static void __init cf_check dbc_uart_init_postirq(struct serial_port *port) break; } #ifdef CONFIG_X86 - /* - * This marks the whole page as R/O, which may include other registers - * unrelated to DbC. Xen needs only DbC area protected, but it seems - * 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, " + "making the whole device R/O (share=no)\n"); + uart->dbc.share = XHCI_SHARE_NONE; + if ( pci_ro_device(0, uart->dbc.sbdf.bus, uart->dbc.sbdf.devfn) ) + printk(XENLOG_WARNING + "Failed to mark read-only %pp used for XHCI console\n", + &uart->dbc.sbdf); + 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"); + } #endif } -- git-series 0.9.1
|
Lists.xenproject.org is hosted with RackSpace, monitoring our |