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[142.79.211.230]) by smtp.gmail.com with ESMTPSA id g25sm1981538ion.32.2021.05.13.17.57.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 13 May 2021 17:57:33 -0700 (PDT) From: Connor Davis To: Greg Kroah-Hartman Cc: Connor Davis , Mathias Nyman , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 4/4] usb: xhci: Notify xen when DbC is unsafe to use Date: Thu, 13 May 2021 18:56:51 -0600 Message-Id: <5c4a8a65a038563f2d20a734d74d2ed4a0f2d69e.1620952511.git.connojdavis@gmail.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- drivers/usb/host/xhci-dbgcap.h | 19 ++++++++++++++ drivers/usb/host/xhci.c | 47 ++++++++++++++++++++++++++++++++++ drivers/usb/host/xhci.h | 1 + 3 files changed, 67 insertions(+) diff --git a/drivers/usb/host/xhci-dbgcap.h b/drivers/usb/host/xhci-dbgcap.h index c70b78d504eb..332be531bebd 100644 --- a/drivers/usb/host/xhci-dbgcap.h +++ b/drivers/usb/host/xhci-dbgcap.h @@ -227,4 +227,23 @@ static inline int xhci_dbc_resume(struct xhci_hcd *xhci) return 0; } #endif /* CONFIG_USB_XHCI_DBGCAP */ + +#ifdef CONFIG_XEN_DOM0 +#include + +int xen_dbgp_reset_prep(struct usb_hcd *hcd); +int xen_dbgp_external_startup(struct usb_hcd *hcd); + +void xhci_dbc_external_reset_prep(struct xhci_hcd *xhci); +void xhci_dbc_external_reset_done(struct xhci_hcd *xhci); +#else +static inline void xhci_dbc_external_reset_prep(struct xhci_hcd *xhci) +{ +} + +static inline void xhci_dbc_external_reset_done(struct xhci_hcd *xhci) +{ +} +#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..3ff7879069ec 100644 --- a/drivers/usb/host/xhci.c +++ b/drivers/usb/host/xhci.c @@ -37,6 +37,47 @@ 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 +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"); + } + } +} + +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; +} +#endif + static bool td_on_ring(struct xhci_td *td, struct xhci_ring *ring) { struct xhci_segment *seg = ring->first_seg; @@ -180,6 +221,8 @@ 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 +254,8 @@ 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 +1036,7 @@ 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 +1271,7 @@ 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