Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Thu, 14 Jul 2022 23:10:17 -0700
In-Reply-To: <20220715061027.1612149-1-kaleshsingh@google.com>
Message-Id: <20220715061027.1612149-9-kaleshsingh@google.com>
Mime-Version: 1.0
References: <20220715061027.1612149-1-kaleshsingh@google.com>
Subject: [PATCH v4 08/18] KVM: arm64: Add PROTECTED_NVHE_STACKTRACE Kconfig
From:   Kalesh Singh <kaleshsingh@google.com>
To:     maz@kernel.org, mark.rutland@arm.com, broonie@kernel.org,
        madvenka@linux.microsoft.com
Cc:     will@kernel.org, qperret@google.com, tabba@google.com,
        kaleshsingh@google.com, james.morse@arm.com,
        alexandru.elisei@arm.com, suzuki.poulose@arm.com,
        catalin.marinas@arm.com, andreyknvl@gmail.com,
        russell.king@oracle.com, vincenzo.frascino@arm.com,
        mhiramat@kernel.org, ast@kernel.org, drjones@redhat.com,
        wangkefeng.wang@huawei.com, elver@google.com, keirf@google.com,
        yuzenghui@huawei.com, ardb@kernel.org, oupton@google.com,
        linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu,
        linux-kernel@vger.kernel.org, android-mm@google.com,
        kernel-team@android.com
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

This can be used to disable stacktrace for the protected KVM
nVHE hypervisor, in order to save on the associated memory usage.

This option is disabled by default, since protected KVM is not widely
used on platforms other than Android currently.

Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
---
 arch/arm64/kvm/Kconfig | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
index 8a5fbbf084df..1edab6f8a3b8 100644
--- a/arch/arm64/kvm/Kconfig
+++ b/arch/arm64/kvm/Kconfig
@@ -46,6 +46,21 @@ menuconfig KVM
 
 	  If unsure, say N.
 
+config PROTECTED_NVHE_STACKTRACE
+	bool "Protected KVM hypervisor stacktraces"
+	depends on KVM
+	default n
+	help
+	  Say Y here to enable pKVM hypervisor stacktraces on hyp_panic()
+
+	  If you are not using protected nVHE (pKVM), say N.
+
+	  If using protected nVHE mode, but cannot afford the associated
+	  memory cost (less than 0.75 page per CPU) of pKVM stacktraces,
+	  say N.
+
+	  If unsure, say N.
+
 config NVHE_EL2_DEBUG
 	bool "Debug mode for non-VHE EL2 object"
 	depends on KVM
-- 
2.37.0.170.g444d1eabd0-goog