linux-kernel - [PATCH 1/7] KVM: arm64: Map the stack pages in the 'private' range

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Message-Id: <20220210224220.4076151-2-kaleshsingh@google.com>
Date:   Thu, 10 Feb 2022 14:41:42 -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 1/7] KVM: arm64: Map the stack pages in the 'private' range

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

In preparation for introducing guard pages for the stacks, map them
in the 'private' range of the EL2 VA space in which the VA to PA
relation is flexible when running in protected mode.

Signed-off-by: Quentin Perret <qperret@...gle.com>
[Kalesh - Refactor, add comments, resolve conflicts,
          use  __pkvm_create_private_mapping()]
Signed-off-by: Kalesh Singh <kaleshsingh@...gle.com>
---
 arch/arm64/kvm/hyp/nvhe/setup.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kvm/hyp/nvhe/setup.c b/arch/arm64/kvm/hyp/nvhe/setup.c
index 27af337f9fea..99e178cf4249 100644
--- a/arch/arm64/kvm/hyp/nvhe/setup.c
+++ b/arch/arm64/kvm/hyp/nvhe/setup.c
@@ -105,11 +105,19 @@ static int recreate_hyp_mappings(phys_addr_t phys, unsigned long size,
 		if (ret)
 			return ret;
 
-		end = (void *)per_cpu_ptr(&kvm_init_params, i)->stack_hyp_va;
+		/* Map stack pages in the 'private' VA range */
+		end = (void *)__hyp_pa(per_cpu_ptr(&kvm_init_params, i)->stack_hyp_va);
 		start = end - PAGE_SIZE;
-		ret = pkvm_create_mappings(start, end, PAGE_HYP);
-		if (ret)
-			return ret;
+		start = (void *)__pkvm_create_private_mapping((phys_addr_t)start,
+					PAGE_SIZE, PAGE_HYP);
+		if (IS_ERR_OR_NULL(start))
+			return PTR_ERR(start);
+		end = start + PAGE_SIZE;
+		/*
+		 * Update stack_hyp_va to the end of the stack page's
+		 * allocated 'private' VA range.
+		 */
+		per_cpu_ptr(&kvm_init_params, i)->stack_hyp_va = (unsigned long) end;
 	}
 
 	/*
-- 
2.35.1.265.g69c8d7142f-goog