linux-kernel - [PATCH v4 23/26] kvm: arm64: Intercept host's SYSTEM

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Message-Id: <20201202184122.26046-24-dbrazdil@google.com>
Date:   Wed,  2 Dec 2020 18:41:19 +0000
From:   David Brazdil <dbrazdil@...gle.com>
To:     kvmarm@...ts.cs.columbia.edu
Cc:     Jonathan Corbet <corbet@....net>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Marc Zyngier <maz@...nel.org>,
        James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Dennis Zhou <dennis@...nel.org>, Tejun Heo <tj@...nel.org>,
        Christoph Lameter <cl@...ux.com>,
        Mark Rutland <mark.rutland@....com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Sudeep Holla <sudeep.holla@....com>, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        kernel-team@...roid.com, David Brazdil <dbrazdil@...gle.com>
Subject: [PATCH v4 23/26] kvm: arm64: Intercept host's SYSTEM_SUSPEND PSCI SMCs

Add a handler of SYSTEM_SUSPEND host PSCI SMCs. The semantics are
equivalent to CPU_SUSPEND, typically called on the last online CPU.
Reuse the same entry point and boot args struct as CPU_SUSPEND.

Signed-off-by: David Brazdil <dbrazdil@...gle.com>
---
 arch/arm64/kvm/hyp/nvhe/hyp-init.S   |  2 +-
 arch/arm64/kvm/hyp/nvhe/psci-relay.c | 26 ++++++++++++++++++++++++++
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-init.S b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
index 0853f62b052b..a2e251547625 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-init.S
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
@@ -151,7 +151,7 @@ SYM_CODE_START(kvm_hyp_cpu_entry)
 SYM_CODE_END(kvm_hyp_cpu_entry)
 
 /*
- * PSCI CPU_SUSPEND entry point
+ * PSCI CPU_SUSPEND / SYSTEM_SUSPEND entry point
  *
  * x0: struct kvm_nvhe_init_params PA
  */
diff --git a/arch/arm64/kvm/hyp/nvhe/psci-relay.c b/arch/arm64/kvm/hyp/nvhe/psci-relay.c
index 688cf7f40d42..08dc9de69314 100644
--- a/arch/arm64/kvm/hyp/nvhe/psci-relay.c
+++ b/arch/arm64/kvm/hyp/nvhe/psci-relay.c
@@ -201,6 +201,30 @@ static int psci_cpu_suspend(u64 func_id, struct kvm_cpu_context *host_ctxt)
 			 __hyp_pa(init_params));
 }
 
+static int psci_system_suspend(u64 func_id, struct kvm_cpu_context *host_ctxt)
+{
+	DECLARE_REG(unsigned long, pc, host_ctxt, 1);
+	DECLARE_REG(unsigned long, r0, host_ctxt, 2);
+
+	struct psci_boot_args *boot_args;
+	struct kvm_nvhe_init_params *init_params;
+
+	boot_args = this_cpu_ptr(hyp_symbol_addr(suspend_args));
+	init_params = this_cpu_ptr(hyp_symbol_addr(kvm_init_params));
+
+	/*
+	 * No need to acquire a lock before writing to boot_args because a core
+	 * can only suspend itself. Racy CPU_ON calls use a separate struct.
+	 */
+	boot_args->pc = pc;
+	boot_args->r0 = r0;
+
+	/* Will only return on error. */
+	return psci_call(func_id,
+			 __hyp_pa(hyp_symbol_addr(kvm_hyp_cpu_resume)),
+			 __hyp_pa(init_params), 0);
+}
+
 asmlinkage void __noreturn kvm_host_psci_cpu_entry(bool is_cpu_on)
 {
 	struct psci_boot_args *boot_args;
@@ -265,6 +289,8 @@ static unsigned long psci_1_0_handler(u64 func_id, struct kvm_cpu_context *host_
 	case PSCI_1_0_FN_SET_SUSPEND_MODE:
 	case PSCI_1_1_FN64_SYSTEM_RESET2:
 		return psci_forward(host_ctxt);
+	case PSCI_1_0_FN64_SYSTEM_SUSPEND:
+		return psci_system_suspend(func_id, host_ctxt);
 	default:
 		return psci_0_2_handler(func_id, host_ctxt);
 	}
-- 
2.29.2.454.gaff20da3a2-goog