linux-kernel - [RFC PATCH 08/26] kvm: arm64: Create nVHE copy of cpu_logical

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Message-Id: <20201104183630.27513-9-dbrazdil@google.com>
Date:   Wed,  4 Nov 2020 18:36:12 +0000
From:   David Brazdil <dbrazdil@...gle.com>
To:     kvmarm@...ts.cs.columbia.edu
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Marc Zyngier <maz@...nel.org>,
        James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, 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>,
        Quentin Perret <qperret@...gle.com>,
        Andrew Scull <ascull@...gle.com>, kernel-team@...roid.com,
        David Brazdil <dbrazdil@...gle.com>
Subject: [RFC PATCH 08/26] kvm: arm64: Create nVHE copy of cpu_logical_map

When KVM starts validating host's PSCI requests, it will need to map
MPIDR back to the CPU ID. To this end, copy cpu_logical_map into nVHE
hyp memory when KVM is initialized.

Only copy the information for CPUs that are online at the point of KVM
initialization so that KVM rejects CPUs whose features were not checked
against the finalized capabilities.

Signed-off-by: David Brazdil <dbrazdil@...gle.com>
---
 arch/arm64/kvm/arm.c             | 17 +++++++++++++++++
 arch/arm64/kvm/hyp/nvhe/percpu.c | 16 ++++++++++++++++
 2 files changed, 33 insertions(+)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 8bb9fffe2a8f..58e9cc183bd5 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1481,6 +1481,21 @@ static inline void hyp_cpu_pm_exit(void)
 }
 #endif
 
+static void init_cpu_logical_map(void)
+{
+	extern u64 kvm_nvhe_sym(__cpu_logical_map)[NR_CPUS];
+	int cpu;
+
+	/*
+	 * Copy the MPIDR <-> logical CPU ID mapping to hyp.
+	 * Only copy the set of online CPUs whose features have been chacked
+	 * against the finalized system capabilities. The hypervisor will not
+	 * allow any other CPUs from the `possible` set to boot.
+	 */
+	for_each_online_cpu(cpu)
+		CHOOSE_NVHE_SYM(__cpu_logical_map)[cpu] = cpu_logical_map(cpu);
+}
+
 static int init_common_resources(void)
 {
 	return kvm_set_ipa_limit();
@@ -1658,6 +1673,8 @@ static int init_hyp_mode(void)
 		}
 	}
 
+	init_cpu_logical_map();
+
 	return 0;
 
 out_err:
diff --git a/arch/arm64/kvm/hyp/nvhe/percpu.c b/arch/arm64/kvm/hyp/nvhe/percpu.c
index 5fd0c5696907..8b7f6b7dbd48 100644
--- a/arch/arm64/kvm/hyp/nvhe/percpu.c
+++ b/arch/arm64/kvm/hyp/nvhe/percpu.c
@@ -8,6 +8,22 @@
 #include <asm/kvm_hyp.h>
 #include <asm/kvm_mmu.h>
 
+/*
+ * nVHE copy of data structures tracking available CPU cores.
+ * Only entries for CPUs that were online at KVM init are populated.
+ * Other CPUs should not be allowed to boot because their features were
+ * not checked against the finalized system capabilities.
+ */
+u64 __cpu_logical_map[NR_CPUS] = { [0 ... NR_CPUS-1] = INVALID_HWID };
+
+u64 cpu_logical_map(int cpu)
+{
+	if (cpu < 0 || cpu >= ARRAY_SIZE(__cpu_logical_map))
+		hyp_panic();
+
+	return __cpu_logical_map[cpu];
+}
+
 unsigned long __hyp_per_cpu_offset(unsigned int cpu)
 {
 	unsigned long *cpu_base_array;
-- 
2.29.1.341.ge80a0c044ae-goog