When running as a dom0 guest on Xen, check if the USB3 debug
capability is enabled before xHCI reset, suspend, and resume. If it
is, call xen_dbgp_reset_prep() to notify Xen that it is unsafe to touch
MMIO registers until the next xen_dbgp_external_startup().
This notification allows Xen to avoid undefined behavior resulting
from MMIO access when the host controller's CNR bit is set or when
the device transitions to D3hot.
Signed-off-by: Connor Davis <connojdavis@gmail.com>
---
drivers/usb/host/xhci-dbgcap.h | 6 ++++
drivers/usb/host/xhci.c | 57 ++++++++++++++++++++++++++++++++++
drivers/usb/host/xhci.h | 1 +
3 files changed, 64 insertions(+)
diff --git a/drivers/usb/host/xhci-dbgcap.h b/drivers/usb/host/xhci-dbgcap.h
index c70b78d504eb..24784b82a840 100644
--- a/drivers/usb/host/xhci-dbgcap.h
+++ b/drivers/usb/host/xhci-dbgcap.h
@@ -227,4 +227,10 @@ static inline int xhci_dbc_resume(struct xhci_hcd *xhci)
return 0;
}
#endif /* CONFIG_USB_XHCI_DBGCAP */
+
+#ifdef CONFIG_XEN_DOM0
+int xen_dbgp_reset_prep(struct usb_hcd *hcd);
+int xen_dbgp_external_startup(struct usb_hcd *hcd);
+#endif /* CONFIG_XEN_DOM0 */
+
#endif /* __LINUX_XHCI_DBGCAP_H */
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index ca9385d22f68..afe44169183f 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -37,6 +37,57 @@ static unsigned long long quirks;
module_param(quirks, ullong, S_IRUGO);
MODULE_PARM_DESC(quirks, "Bit flags for quirks to be enabled as default");
+#ifdef CONFIG_XEN_DOM0
+#include <xen/xen.h>
+
+static void xhci_dbc_external_reset_prep(struct xhci_hcd *xhci)
+{
+ struct dbc_regs __iomem *regs;
+ void __iomem *base;
+ int dbc_cap;
+
+ if (!xen_initial_domain())
+ return;
+
+ base = &xhci->cap_regs->hc_capbase;
+ dbc_cap = xhci_find_next_ext_cap(base, 0, XHCI_EXT_CAPS_DEBUG);
+
+ if (!dbc_cap)
+ return;
+
+ xhci->external_dbc = 0;
+ regs = base + dbc_cap;
+
+ if (readl(®s->control) & DBC_CTRL_DBC_ENABLE) {
+ if (xen_dbgp_reset_prep(xhci_to_hcd(xhci)))
+ xhci_dbg_trace(xhci, trace_xhci_dbg_init,
+ "// Failed to reset external DBC");
+ else {
+ xhci->external_dbc = 1;
+ xhci_dbg_trace(xhci, trace_xhci_dbg_init,
+ "// Completed reset of external DBC");
+ }
+ }
+}
+
+static void xhci_dbc_external_reset_done(struct xhci_hcd *xhci)
+{
+ if (!xen_initial_domain() || !xhci->external_dbc)
+ return;
+
+ if (xen_dbgp_external_startup(xhci_to_hcd(xhci)))
+ xhci->external_dbc = 0;
+}
+#else
+static void xhci_dbc_external_reset_prep(struct xhci_hcd *xhci)
+{
+}
+
+static void xhci_dbc_external_reset_done(struct xhci_hcd *xhci)
+{
+}
+#endif
+
static bool td_on_ring(struct xhci_td *td, struct xhci_ring *ring)
{
struct xhci_segment *seg = ring->first_seg;
@@ -180,6 +231,8 @@ int xhci_reset(struct xhci_hcd *xhci)
return 0;
}
+ xhci_dbc_external_reset_prep(xhci);
+
xhci_dbg_trace(xhci, trace_xhci_dbg_init, "// Reset the HC");
command = readl(&xhci->op_regs->command);
command |= CMD_RESET;
@@ -211,6 +264,8 @@ int xhci_reset(struct xhci_hcd *xhci)
*/
ret = xhci_handshake(&xhci->op_regs->status,
STS_CNR, 0, 10 * 1000 * 1000);
+ if (!ret)
+ xhci_dbc_external_reset_done(xhci);
xhci->usb2_rhub.bus_state.port_c_suspend = 0;
xhci->usb2_rhub.bus_state.suspended_ports = 0;
@@ -991,6 +1046,7 @@ int xhci_suspend(struct xhci_hcd *xhci, bool do_wakeup)
return 0;
xhci_dbc_suspend(xhci);
+ xhci_dbc_external_reset_prep(xhci);
/* Don't poll the roothubs on bus suspend. */
xhci_dbg(xhci, "%s: stopping port polling.\n", __func__);
@@ -1225,6 +1281,7 @@ int xhci_resume(struct xhci_hcd *xhci, bool hibernated)
spin_unlock_irq(&xhci->lock);
xhci_dbc_resume(xhci);
+ xhci_dbc_external_reset_done(xhci);
done:
if (retval == 0) {
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 2595a8f057c4..61d8efc9eef2 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1920,6 +1920,7 @@ struct xhci_hcd {
struct list_head regset_list;
void *dbc;
+ int external_dbc;
/* platform-specific data -- must come last */
unsigned long priv[] __aligned(sizeof(s64));
};
--
2.31.1
On Tue, May 11, 2021 at 06:18:21PM -0600, Connor Davis wrote: > When running as a dom0 guest on Xen, check if the USB3 debug > capability is enabled before xHCI reset, suspend, and resume. If it > is, call xen_dbgp_reset_prep() to notify Xen that it is unsafe to touch > MMIO registers until the next xen_dbgp_external_startup(). > > This notification allows Xen to avoid undefined behavior resulting > from MMIO access when the host controller's CNR bit is set or when > the device transitions to D3hot. > > Signed-off-by: Connor Davis <connojdavis@gmail.com> > --- > drivers/usb/host/xhci-dbgcap.h | 6 ++++ > drivers/usb/host/xhci.c | 57 ++++++++++++++++++++++++++++++++++ > drivers/usb/host/xhci.h | 1 + > 3 files changed, 64 insertions(+) > > diff --git a/drivers/usb/host/xhci-dbgcap.h b/drivers/usb/host/xhci-dbgcap.h > index c70b78d504eb..24784b82a840 100644 > --- a/drivers/usb/host/xhci-dbgcap.h > +++ b/drivers/usb/host/xhci-dbgcap.h > @@ -227,4 +227,10 @@ static inline int xhci_dbc_resume(struct xhci_hcd *xhci) > return 0; > } > #endif /* CONFIG_USB_XHCI_DBGCAP */ > + > +#ifdef CONFIG_XEN_DOM0 > +int xen_dbgp_reset_prep(struct usb_hcd *hcd); > +int xen_dbgp_external_startup(struct usb_hcd *hcd); > +#endif /* CONFIG_XEN_DOM0 */ > + > #endif /* __LINUX_XHCI_DBGCAP_H */ > diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c > index ca9385d22f68..afe44169183f 100644 > --- a/drivers/usb/host/xhci.c > +++ b/drivers/usb/host/xhci.c > @@ -37,6 +37,57 @@ static unsigned long long quirks; > module_param(quirks, ullong, S_IRUGO); > MODULE_PARM_DESC(quirks, "Bit flags for quirks to be enabled as default"); > > +#ifdef CONFIG_XEN_DOM0 > +#include <xen/xen.h> <snip> Can't this #ifdef stuff go into a .h file? thanks, greg k-h
On May 12, 21, Greg Kroah-Hartman wrote: > On Tue, May 11, 2021 at 06:18:21PM -0600, Connor Davis wrote: > > When running as a dom0 guest on Xen, check if the USB3 debug > > capability is enabled before xHCI reset, suspend, and resume. If it > > is, call xen_dbgp_reset_prep() to notify Xen that it is unsafe to touch > > MMIO registers until the next xen_dbgp_external_startup(). > > > > This notification allows Xen to avoid undefined behavior resulting > > from MMIO access when the host controller's CNR bit is set or when > > the device transitions to D3hot. > > > > Signed-off-by: Connor Davis <connojdavis@gmail.com> > > --- > > drivers/usb/host/xhci-dbgcap.h | 6 ++++ > > drivers/usb/host/xhci.c | 57 ++++++++++++++++++++++++++++++++++ > > drivers/usb/host/xhci.h | 1 + > > 3 files changed, 64 insertions(+) > > > > diff --git a/drivers/usb/host/xhci-dbgcap.h b/drivers/usb/host/xhci-dbgcap.h > > index c70b78d504eb..24784b82a840 100644 > > --- a/drivers/usb/host/xhci-dbgcap.h > > +++ b/drivers/usb/host/xhci-dbgcap.h > > @@ -227,4 +227,10 @@ static inline int xhci_dbc_resume(struct xhci_hcd *xhci) > > return 0; > > } > > #endif /* CONFIG_USB_XHCI_DBGCAP */ > > + > > +#ifdef CONFIG_XEN_DOM0 > > +int xen_dbgp_reset_prep(struct usb_hcd *hcd); > > +int xen_dbgp_external_startup(struct usb_hcd *hcd); > > +#endif /* CONFIG_XEN_DOM0 */ > > + > > #endif /* __LINUX_XHCI_DBGCAP_H */ > > diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c > > index ca9385d22f68..afe44169183f 100644 > > --- a/drivers/usb/host/xhci.c > > +++ b/drivers/usb/host/xhci.c > > @@ -37,6 +37,57 @@ static unsigned long long quirks; > > module_param(quirks, ullong, S_IRUGO); > > MODULE_PARM_DESC(quirks, "Bit flags for quirks to be enabled as default"); > > > > +#ifdef CONFIG_XEN_DOM0 > > +#include <xen/xen.h> > > <snip> > > Can't this #ifdef stuff go into a .h file? > Yep, will clean that up in v2. > thanks, > > greg k-h Thanks, Connor
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