linux-kernel - [PATCH 2/7] KVM: arm64: Factor out private range VA allocation

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Date:   Thu, 10 Feb 2022 14:41:43 -0800
From:   Kalesh Singh <kaleshsingh@...gle.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     will@...nel.org, maz@...nel.org, qperret@...gle.com,
        tabba@...gle.com, surenb@...gle.com, kernel-team@...roid.com,
        Kalesh Singh <kaleshsingh@...gle.com>,
        Catalin Marinas <catalin.marinas@....com>,
        James Morse <james.morse@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Ard Biesheuvel <ardb@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Pasha Tatashin <pasha.tatashin@...een.com>,
        Joey Gouly <joey.gouly@....com>,
        Peter Collingbourne <pcc@...gle.com>,
        Andrew Walbran <qwandor@...gle.com>,
        Andrew Scull <ascull@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kvmarm@...ts.cs.columbia.edu
Subject: [PATCH 2/7] KVM: arm64: Factor out private range VA allocation

From: Quentin Perret <qperret@...gle.com>

__pkvm_create_private_mapping() is currently responsible for allocating
VA space in the hypervisor's "private" range and creating stage-1
mappings. In order to allow reusing the VA space allocation logic from
other places, let's factor it out in a standalone function. This is will
be used to allocate private VA ranges for hypervisor stack guard pages
in a subsequent patch in this series.

Signed-off-by: Quentin Perret <qperret@...gle.com>
[Kalesh - Resolve conflicts and make hyp_alloc_private_va_range
          available outside nvhe/mm.c, update commit message]
Signed-off-by: Kalesh Singh <kaleshsingh@...gle.com>
---
 arch/arm64/kvm/hyp/include/nvhe/mm.h |  1 +
 arch/arm64/kvm/hyp/nvhe/mm.c         | 28 +++++++++++++++++++---------
 2 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/kvm/hyp/include/nvhe/mm.h b/arch/arm64/kvm/hyp/include/nvhe/mm.h
index 2d08510c6cc1..f53fb0e406db 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/mm.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/mm.h
@@ -21,6 +21,7 @@ int pkvm_create_mappings(void *from, void *to, enum kvm_pgtable_prot prot);
 int pkvm_create_mappings_locked(void *from, void *to, enum kvm_pgtable_prot prot);
 unsigned long __pkvm_create_private_mapping(phys_addr_t phys, size_t size,
 					    enum kvm_pgtable_prot prot);
+unsigned long hyp_alloc_private_va_range(size_t size);
 
 static inline void hyp_vmemmap_range(phys_addr_t phys, unsigned long size,
 				     unsigned long *start, unsigned long *end)
diff --git a/arch/arm64/kvm/hyp/nvhe/mm.c b/arch/arm64/kvm/hyp/nvhe/mm.c
index 526a7d6fa86f..e196441e072f 100644
--- a/arch/arm64/kvm/hyp/nvhe/mm.c
+++ b/arch/arm64/kvm/hyp/nvhe/mm.c
@@ -37,6 +37,22 @@ static int __pkvm_create_mappings(unsigned long start, unsigned long size,
 	return err;
 }
 
+unsigned long hyp_alloc_private_va_range(size_t size)
+{
+	unsigned long addr = __io_map_base;
+
+	hyp_assert_lock_held(&pkvm_pgd_lock);
+	__io_map_base += PAGE_ALIGN(size);
+
+	/* Are we overflowing on the vmemmap ? */
+	if (__io_map_base > __hyp_vmemmap) {
+		__io_map_base = addr;
+		addr = (unsigned long)ERR_PTR(-ENOMEM);
+	}
+
+	return addr;
+}
+
 unsigned long __pkvm_create_private_mapping(phys_addr_t phys, size_t size,
 					    enum kvm_pgtable_prot prot)
 {
@@ -45,16 +61,10 @@ unsigned long __pkvm_create_private_mapping(phys_addr_t phys, size_t size,
 
 	hyp_spin_lock(&pkvm_pgd_lock);
 
-	size = PAGE_ALIGN(size + offset_in_page(phys));
-	addr = __io_map_base;
-	__io_map_base += size;
-
-	/* Are we overflowing on the vmemmap ? */
-	if (__io_map_base > __hyp_vmemmap) {
-		__io_map_base -= size;
-		addr = (unsigned long)ERR_PTR(-ENOMEM);
+	size = size + offset_in_page(phys);
+	addr = hyp_alloc_private_va_range(size);
+	if (IS_ERR((void *)addr))
 		goto out;
-	}
 
 	err = kvm_pgtable_hyp_map(&pkvm_pgtable, addr, size, phys, prot);
 	if (err) {
-- 
2.35.1.265.g69c8d7142f-goog