[PATCH v3 18/23] kvm: arm64: Add function to enter host from KVM nVHE hyp code

From: David Brazdil <dbrazdil@google.com>
To: kvmarm@lists.cs.columbia.edu
Cc: Jonathan Corbet <corbet@lwn.net>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>,
	James Morse <james.morse@arm.com>,
	Julien Thierry <julien.thierry.kdev@gmail.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Dennis Zhou <dennis@kernel.org>, Tejun Heo <tj@kernel.org>,
	Christoph Lameter <cl@linux.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Sudeep Holla <sudeep.holla@arm.com>,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, kernel-team@android.com,
	David Brazdil <dbrazdil@google.com>
Subject: [PATCH v3 18/23] kvm: arm64: Add function to enter host from KVM nVHE hyp code
Date: Thu, 26 Nov 2020 15:54:16 +0000	[thread overview]
Message-ID: <20201126155421.14901-19-dbrazdil@google.com> (raw)
In-Reply-To: <20201126155421.14901-1-dbrazdil@google.com>

All nVHE hyp code is currently executed as handlers of host's HVCs. This
will change as nVHE starts intercepting host's PSCI CPU_ON SMCs. The
newly booted CPU will need to initialize EL2 state and then enter the
host. Add __host_enter function that branches into the existing
host state-restoring code after the trap handler would have returned.

Signed-off-by: David Brazdil <dbrazdil@google.com>
---
 arch/arm64/kvm/hyp/nvhe/host.S | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/arm64/kvm/hyp/nvhe/host.S b/arch/arm64/kvm/hyp/nvhe/host.S
index 2b56f0bdf874..a820dfdc9c25 100644
--- a/arch/arm64/kvm/hyp/nvhe/host.S
+++ b/arch/arm64/kvm/hyp/nvhe/host.S
@@ -39,6 +39,7 @@ SYM_FUNC_START(__host_exit)
 	bl	handle_trap
 
 	/* Restore host regs x0-x17 */
+__host_enter_restore_full:
 	ldp	x0, x1,   [x29, #CPU_XREG_OFFSET(0)]
 	ldp	x2, x3,   [x29, #CPU_XREG_OFFSET(2)]
 	ldp	x4, x5,   [x29, #CPU_XREG_OFFSET(4)]
@@ -61,6 +62,14 @@ __host_enter_without_restoring:
 	sb
 SYM_FUNC_END(__host_exit)
 
+/*
+ * void __noreturn __host_enter(struct kvm_cpu_context *host_ctxt);
+ */
+SYM_FUNC_START(__host_enter)
+	mov	x29, x0
+	b	__host_enter_restore_full
+SYM_FUNC_END(__host_enter)
+
 /*
  * void __noreturn __hyp_do_panic(bool restore_host, u64 spsr, u64 elr, u64 par);
  */
-- 
2.29.2.454.gaff20da3a2-goog

