From mboxrd@z Thu Jan 1 00:00:00 1970 From: amit.kachhap@arm.com (Amit Daniel Kachhap) Date: Wed, 17 Oct 2018 16:17:59 +0530 Subject: [PATCH v3 6/7] arm64: docs: document KVM support of pointer authentication In-Reply-To: <1539773280-4159-1-git-send-email-amit.kachhap@arm.com> References: <1539773280-4159-1-git-send-email-amit.kachhap@arm.com> Message-ID: <1539773280-4159-7-git-send-email-amit.kachhap@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org The documentation is updated to help in using pointer authentication for KVM guests. Signed-off-by: Amit Daniel Kachhap Cc: Mark Rutland Cc: Christoffer Dall Cc: Marc Zyngier Cc: kvmarm at lists.cs.columbia.edu --- Documentation/arm64/pointer-authentication.txt | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/Documentation/arm64/pointer-authentication.txt b/Documentation/arm64/pointer-authentication.txt index 8a9cb57..b00d735 100644 --- a/Documentation/arm64/pointer-authentication.txt +++ b/Documentation/arm64/pointer-authentication.txt @@ -78,7 +78,13 @@ to TTBR1 addresses (e.g. kernel pointers). Virtualization -------------- -Pointer authentication is not currently supported in KVM guests. KVM +Pointer authentication is enabled in KVM guest when virtual machine is +created by passing a flag requesting this feature to be enabled. Without +this flag, pointer authentication is not enabled in KVM guests and KVM will mask the feature bits from ID_AA64ISAR1_EL1, and attempted use of the feature will result in an UNDEFINED exception being injected into the guest. + +The flag to enable this feature is KVM_ARM_VCPU_PTRAUTH and should be +used in KVM API KVM_ARM_VCPU_INIT. The pointer authentication key +registers are hidden from userspace if this feature is not enabled. -- 2.7.4