linux-kernel - [RFC PATCH 2/4] KVM: arm64: Add an independent API for coalescing tables

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Date:   Mon, 8 Feb 2021 19:22:48 +0800
From:   Yanan Wang <wangyanan55@...wei.com>
To:     Marc Zyngier <maz@...nel.org>, Will Deacon <will@...nel.org>,
        "Catalin Marinas" <catalin.marinas@....com>,
        James Morse <james.morse@....com>,
        "Julien Thierry" <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Gavin Shan <gshan@...hat.com>,
        Quentin Perret <qperret@...gle.com>,
        <kvmarm@...ts.cs.columbia.edu>,
        <linux-arm-kernel@...ts.infradead.org>, <kvm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
CC:     <wanghaibin.wang@...wei.com>, <zhukeqian1@...wei.com>,
        <yuzenghui@...wei.com>, Yanan Wang <wangyanan55@...wei.com>
Subject: [RFC PATCH 2/4] KVM: arm64: Add an independent API for coalescing tables

Process of coalescing page mappings back to a block mapping is different
from normal map path, such as TLB invalidation and CMOs, so here add an
independent API for this case.

Signed-off-by: Yanan Wang <wangyanan55@...wei.com>
---
 arch/arm64/kvm/hyp/pgtable.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 2f4f87021980..78a560446f80 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -525,6 +525,24 @@ static int stage2_map_walker_try_leaf(u64 addr, u64 end, u32 level,
 	return 0;
 }
 
+static void stage2_coalesce_tables_into_block(u64 addr, u32 level,
+					      kvm_pte_t *ptep,
+					      struct stage2_map_data *data)
+{
+	u64 granule = kvm_granule_size(level), phys = data->phys;
+	kvm_pte_t new = kvm_init_valid_leaf_pte(phys, data->attr, level);
+
+	kvm_set_invalid_pte(ptep);
+
+	/*
+	 * Invalidate the whole stage-2, as we may have numerous leaf entries
+	 * below us which would otherwise need invalidating individually.
+	 */
+	kvm_call_hyp(__kvm_tlb_flush_vmid, data->mmu);
+	smp_store_release(ptep, new);
+	data->phys += granule;
+}
+
 static int stage2_map_walk_table_pre(u64 addr, u64 end, u32 level,
 				     kvm_pte_t *ptep,
 				     struct stage2_map_data *data)
-- 
2.23.0