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From: Michael Kelley <mikelley@microsoft.com>
To: will@kernel.org, catalin.marinas@arm.com, mark.rutland@arm.com,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org,
	linux-efi@vger.kernel.org, wei.liu@kernel.org, kys@microsoft.com,
	sthemmin@microsoft.com, ardb@kernel.org
Cc: mikelley@microsoft.com
Subject: [PATCH v12 2/5] arm64: hyperv: Add panic handler
Date: Wed,  4 Aug 2021 08:52:36 -0700	[thread overview]
Message-ID: <1628092359-61351-3-git-send-email-mikelley@microsoft.com> (raw)
In-Reply-To: <1628092359-61351-1-git-send-email-mikelley@microsoft.com>

Add a function to inform Hyper-V about a guest panic.

This code is built only when CONFIG_HYPERV is enabled.

Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Sunil Muthuswamy <sunilmut@microsoft.com>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>

---
 arch/arm64/hyperv/hv_core.c | 52 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)

diff --git a/arch/arm64/hyperv/hv_core.c b/arch/arm64/hyperv/hv_core.c
index 4c5dc0f..b54c347 100644
--- a/arch/arm64/hyperv/hv_core.c
+++ b/arch/arm64/hyperv/hv_core.c
@@ -127,3 +127,55 @@ u64 hv_get_vpreg(u32 msr)
 	return output.as64.low;
 }
 EXPORT_SYMBOL_GPL(hv_get_vpreg);
+
+/*
+ * 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 hv_kmsg_dump() 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, the PC,
+	 * and the SP.
+	 */
+	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->sp);
+	hv_set_vpreg(HV_REGISTER_CRASH_P4, 0);
+
+	/*
+	 * 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);
-- 
1.8.3.1


  parent reply	other threads:[~2021-08-04 15:53 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-04 15:52 [PATCH v12 0/5] Enable Linux guests on Hyper-V on ARM64 Michael Kelley
2021-08-04 15:52 ` [PATCH v12 1/5] arm64: hyperv: Add Hyper-V hypercall and register access utilities Michael Kelley
2021-08-04 15:52 ` Michael Kelley [this message]
2021-08-04 15:52 ` [PATCH v12 3/5] arm64: hyperv: Initialize hypervisor on boot Michael Kelley
2021-08-04 15:52 ` [PATCH v12 4/5] arm64: efi: Export screen_info Michael Kelley
2021-08-04 15:52 ` [PATCH v12 5/5] Drivers: hv: Enable Hyper-V code to be built on ARM64 Michael Kelley
2021-08-04 16:10   ` Catalin Marinas
2021-08-04 16:40     ` Wei Liu
2021-08-04 16:43       ` Michael Kelley
2021-08-04 16:25 ` [PATCH v12 0/5] Enable Linux guests on Hyper-V " Catalin Marinas
2021-08-04 16:37   ` Wei Liu
2021-08-04 16:39   ` Michael Kelley
2021-08-04 16:43     ` Catalin Marinas
2021-08-04 16:58 ` Wei Liu

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