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From: Michael Kelley <mikelley@microsoft.com>
To: will@kernel.org, ardb@kernel.org, arnd@arndb.de,
	catalin.marinas@arm.com, mark.rutland@arm.com, maz@kernel.org,
	linux-arm-kernel@lists.infradead.org, gregkh@linuxfoundation.org,
	linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org,
	linux-efi@vger.kernel.org, linux-arch@vger.kernel.org,
	wei.liu@kernel.org, vkuznets@redhat.com, kys@microsoft.com
Cc: mikelley@microsoft.com, sunilmut@microsoft.com, boqun.feng@gmail.com
Subject: [PATCH v7 06/10] arm64: hyperv: Add kexec and panic handlers
Date: Mon, 24 Aug 2020 09:46:19 -0700
Message-ID: <1598287583-71762-7-git-send-email-mikelley@microsoft.com> (raw)
In-Reply-To: <1598287583-71762-1-git-send-email-mikelley@microsoft.com>

Add functions to set up and remove kexec and panic
handlers, and to inform Hyper-V about a guest panic.
These functions are called from architecture independent
code in the VMbus driver.

This code is built only when CONFIG_HYPERV is enabled.

Signed-off-by: Michael Kelley <mikelley@microsoft.com>
---
 arch/arm64/hyperv/hv_core.c       | 80 +++++++++++++++++++++++++++++++++++++++
 arch/arm64/hyperv/mshyperv.c      | 26 +++++++++++++
 arch/arm64/include/asm/mshyperv.h |  2 +
 3 files changed, 108 insertions(+)

diff --git a/arch/arm64/hyperv/hv_core.c b/arch/arm64/hyperv/hv_core.c
index 14e41b7..966d815 100644
--- a/arch/arm64/hyperv/hv_core.c
+++ b/arch/arm64/hyperv/hv_core.c
@@ -211,3 +211,83 @@ void hv_get_vpreg_128(u32 msr, struct hv_get_vp_registers_output *res)
 	kfree(output);
 }
 EXPORT_SYMBOL_GPL(hv_get_vpreg_128);
+
+
+/*
+ * hyperv_report_panic - report a panic to Hyper-V.  This function uses
+ * the older version of the Hyper-V interface that admittedly doesn't
+ * pass enough information to be useful beyond just recording the
+ * occurrence of a panic. The parallel hyperv_report_panic_msg() uses the
+ * new interface that allows reporting 4 Kbytes of data, which is much
+ * more useful. Hyper-V on ARM64 always supports the newer interface, but
+ * we retain support for the older version because the sysadmin is allowed
+ * to disable the newer version via sysctl in case of information security
+ * concerns about the more verbose version.
+ */
+void hyperv_report_panic(struct pt_regs *regs, long err, bool in_die)
+{
+	static bool panic_reported;
+	u64 guest_id;
+
+	/* Don't report a panic to Hyper-V if we're not going to panic */
+	if (in_die && !panic_on_oops)
+		return;
+
+	/*
+	 * We prefer to report panic on 'die' chain as we have proper
+	 * registers to report, but if we miss it (e.g. on BUG()) we need
+	 * to report it on 'panic'.
+	 *
+	 * Calling code in the 'die' and 'panic' paths ensures that only
+	 * one CPU is running this code, so no atomicity is needed.
+	 */
+	if (panic_reported)
+		return;
+	panic_reported = true;
+
+	guest_id = hv_get_vpreg(HV_REGISTER_GUEST_OSID);
+
+	/*
+	 * Hyper-V provides the ability to store only 5 values.
+	 * Pick the passed in error value, the guest_id, and the PC.
+	 * The first two general registers are added arbitrarily.
+	 */
+	hv_set_vpreg(HV_REGISTER_CRASH_P0, err);
+	hv_set_vpreg(HV_REGISTER_CRASH_P1, guest_id);
+	hv_set_vpreg(HV_REGISTER_CRASH_P2, regs->pc);
+	hv_set_vpreg(HV_REGISTER_CRASH_P3, regs->regs[0]);
+	hv_set_vpreg(HV_REGISTER_CRASH_P4, regs->regs[1]);
+
+	/*
+	 * Let Hyper-V know there is crash data available
+	 */
+	hv_set_vpreg(HV_REGISTER_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY);
+}
+EXPORT_SYMBOL_GPL(hyperv_report_panic);
+
+/*
+ * hyperv_report_panic_msg - report panic message to Hyper-V
+ * @pa: physical address of the panic page containing the message
+ * @size: size of the message in the page
+ */
+void hyperv_report_panic_msg(phys_addr_t pa, size_t size)
+{
+	/*
+	 * P3 to contain the physical address of the panic page & P4 to
+	 * contain the size of the panic data in that page. Rest of the
+	 * registers are no-op when the NOTIFY_MSG flag is set.
+	 */
+	hv_set_vpreg(HV_REGISTER_CRASH_P0, 0);
+	hv_set_vpreg(HV_REGISTER_CRASH_P1, 0);
+	hv_set_vpreg(HV_REGISTER_CRASH_P2, 0);
+	hv_set_vpreg(HV_REGISTER_CRASH_P3, pa);
+	hv_set_vpreg(HV_REGISTER_CRASH_P4, size);
+
+	/*
+	 * Let Hyper-V know there is crash data available along with
+	 * the panic message.
+	 */
+	hv_set_vpreg(HV_REGISTER_CRASH_CTL,
+	       (HV_CRASH_CTL_CRASH_NOTIFY | HV_CRASH_CTL_CRASH_NOTIFY_MSG));
+}
+EXPORT_SYMBOL_GPL(hyperv_report_panic_msg);
diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c
index be2cd2f..5bd39cb 100644
--- a/arch/arm64/hyperv/mshyperv.c
+++ b/arch/arm64/hyperv/mshyperv.c
@@ -23,6 +23,8 @@
 
 static void (*vmbus_handler)(void);
 static void (*hv_stimer0_handler)(void);
+static void (*hv_kexec_handler)(void);
+static void (*hv_crash_handler)(struct pt_regs *regs);
 
 static int vmbus_irq;
 static long __percpu *vmbus_evt;
@@ -131,3 +133,27 @@ void hv_remove_stimer0_irq(int irq)
 	}
 }
 EXPORT_SYMBOL_GPL(hv_remove_stimer0_irq);
+
+void hv_setup_kexec_handler(void (*handler)(void))
+{
+	hv_kexec_handler = handler;
+}
+EXPORT_SYMBOL_GPL(hv_setup_kexec_handler);
+
+void hv_remove_kexec_handler(void)
+{
+	hv_kexec_handler = NULL;
+}
+EXPORT_SYMBOL_GPL(hv_remove_kexec_handler);
+
+void hv_setup_crash_handler(void (*handler)(struct pt_regs *regs))
+{
+	hv_crash_handler = handler;
+}
+EXPORT_SYMBOL_GPL(hv_setup_crash_handler);
+
+void hv_remove_crash_handler(void)
+{
+	hv_crash_handler = NULL;
+}
+EXPORT_SYMBOL_GPL(hv_remove_crash_handler);
diff --git a/arch/arm64/include/asm/mshyperv.h b/arch/arm64/include/asm/mshyperv.h
index 2ea64e54..5df96a5 100644
--- a/arch/arm64/include/asm/mshyperv.h
+++ b/arch/arm64/include/asm/mshyperv.h
@@ -149,6 +149,8 @@ static inline int hv_get_vector(void)
 	return vmbus_interrupt;
 }
 
+#define hv_get_crash_ctl(val) \
+		(val = hv_get_vpreg(HV_REGISTER_CRASH_CTL))
 
 /* SMCCC hypercall parameters */
 #define HV_SMCCC_FUNC_NUMBER	1
-- 
1.8.3.1


  parent reply index

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-24 16:46 [PATCH v7 00/10] Enable Linux guests on Hyper-V on ARM64 Michael Kelley
2020-08-24 16:46 ` [PATCH v7 01/10] arm/arm64: smccc-1.1: Add vendor specific owner definition Michael Kelley
2020-08-24 16:46 ` [PATCH v7 02/10] arm64: hyperv: Add core Hyper-V include files Michael Kelley
2020-08-24 18:38   ` Arnd Bergmann
2020-08-24 16:46 ` [PATCH v7 03/10] arm64: hyperv: Add hypercall and register access functions Michael Kelley
2020-08-24 16:46 ` [PATCH v7 04/10] arm64: hyperv: Add memory alloc/free functions for Hyper-V size pages Michael Kelley
2020-08-24 16:46 ` [PATCH v7 05/10] arm64: hyperv: Add interrupt handlers for VMbus and stimer Michael Kelley
2020-08-24 18:54   ` Arnd Bergmann
2020-08-25 22:04     ` Michael Kelley
2020-08-26  7:14       ` Arnd Bergmann
2020-08-24 16:46 ` Michael Kelley [this message]
2020-08-24 16:46 ` [PATCH v7 07/10] arm64: hyperv: Initialize hypervisor on boot Michael Kelley
2020-08-24 18:33   ` Arnd Bergmann
2020-08-25 21:20     ` Michael Kelley
2020-08-26  7:18       ` Arnd Bergmann
2020-08-24 16:46 ` [PATCH v7 08/10] Drivers: hv: vmbus: Add hooks for per-CPU IRQ Michael Kelley
2020-08-24 16:46 ` [PATCH v7 09/10] arm64: efi: Export screen_info Michael Kelley
2020-08-24 17:21   ` Ard Biesheuvel
2020-08-24 17:35   ` Greg KH
2020-08-24 17:40     ` Michael Kelley
2020-08-24 17:52       ` Greg KH
2020-08-24 16:46 ` [PATCH v7 10/10] Drivers: hv: Enable Hyper-V code to be built on ARM64 Michael Kelley
2020-08-24 17:24   ` Ard Biesheuvel
2020-08-24 17:28     ` Michael Kelley
2020-08-25  8:47     ` Ben Dooks

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