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From: David Brazdil <dbrazdil@google.com>
To: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>,
	Dennis Zhou <dennis@kernel.org>, Tejun Heo <tj@kernel.org>,
	Christoph Lameter <cl@linux.com>, Arnd Bergmann <arnd@arndb.de>
Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
	kernel-team@google.com, kvmarm@lists.cs.columbia.edu,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH 7/9] kvm: arm64: Mark hyp stack pages reserved
Date: Wed, 22 Jul 2020 17:44:22 +0100
Message-ID: <20200722164424.42225-8-dbrazdil@google.com> (raw)
In-Reply-To: <20200722164424.42225-1-dbrazdil@google.com>

In preparation for unmapping hyp pages from host stage-2, allocate/free hyp
stack using new helpers which automatically mark the pages reserved.

Signed-off-by: David Brazdil <dbrazdil@google.com>
---
 arch/arm64/kvm/arm.c | 49 ++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 47 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 0700c3d21b23..dc557b380c87 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1451,13 +1451,58 @@ static int init_subsystems(void)
 	return err;
 }
 
+/*
+ * Alloc pages and mark them reserved so the kernel never tries to
+ * take them away from the hypervisor.
+ */
+static unsigned long alloc_hyp_pages(gfp_t flags, unsigned int order)
+{
+	struct page *page;
+	unsigned long i;
+
+	page = alloc_pages(flags, order);
+	if (!page)
+		return 0;
+
+	for (i = 0; i < (1ul << order); ++i)
+		mark_page_reserved(page + i);
+
+	return (unsigned long)page_address(page);
+}
+
+static unsigned long alloc_hyp_page(gfp_t flags)
+{
+	return alloc_hyp_pages(flags, 0);
+}
+
+/*
+ * Free pages which were previously marked reserved for the hypervisor.
+ */
+static void free_hyp_pages(unsigned long addr, unsigned int order)
+{
+	unsigned long i;
+	struct page *page;
+
+	if (!addr)
+		return;
+
+	page = virt_to_page(addr);
+	for (i = 0; i < (1ul << order); ++i)
+		free_reserved_page(page + i);
+}
+
+static void free_hyp_page(unsigned long addr)
+{
+	return free_hyp_pages(addr, 0);
+}
+
 static void teardown_hyp_mode(void)
 {
 	int cpu;
 
 	free_hyp_pgds();
 	for_each_possible_cpu(cpu)
-		free_page(per_cpu(kvm_arm_hyp_stack_page, cpu));
+		free_hyp_page(per_cpu(kvm_arm_hyp_stack_page, cpu));
 }
 
 /**
@@ -1481,7 +1526,7 @@ static int init_hyp_mode(void)
 	for_each_possible_cpu(cpu) {
 		unsigned long stack_page;
 
-		stack_page = __get_free_page(GFP_KERNEL);
+		stack_page = alloc_hyp_page(GFP_KERNEL);
 		if (!stack_page) {
 			err = -ENOMEM;
 			goto out_err;
-- 
2.27.0

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  parent reply index

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-22 16:44 [PATCH 0/9] Independent per-CPU data section for nVHE David Brazdil
2020-07-22 16:44 ` [PATCH 1/9] Macros to override naming of percpu symbols and sections David Brazdil
2020-07-22 16:44 ` [PATCH 2/9] kvm: arm64: Remove __hyp_this_cpu_read David Brazdil
2020-07-22 16:44 ` [PATCH 3/9] kvm: arm64: Remove hyp_adr/ldr_this_cpu David Brazdil
2020-07-22 16:44 ` [PATCH 4/9] kvm: arm64: Add helpers for accessing nVHE hyp per-cpu vars David Brazdil
2020-07-22 16:44 ` [PATCH 5/9] kvm: arm64: Duplicate arm64_ssbd_callback_required for nVHE hyp David Brazdil
2020-07-22 16:44 ` [PATCH 6/9] kvm: arm64: Create separate instances of kvm_host_data for VHE/nVHE David Brazdil
2020-07-22 16:44 ` David Brazdil [this message]
2020-07-22 16:44 ` [PATCH 8/9] kvm: arm64: Set up hyp percpu data for nVHE David Brazdil
2020-07-22 16:44 ` [PATCH 9/9] kvm: arm64: Remove unnecessary hyp mappings David Brazdil

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