[PATCH 1/4] KVM: arm64: Transfer the hyp stack pages out of the host stage-2

[Fuad Tabba <fuad.tabba@linux.dev>]

fix_host_ownership() walks only the linear-map alias of each memblock
region, and the per-CPU hyp stack, mapped in the private VA range for
its guard page, has none.

Walk each stack's VA range with the same walker.

Fixes: 1a919b17ef012 ("KVM: arm64: Add guard pages for pKVM (protected nVHE) hypervisor stack")
Reported-by: Hiroyuki Katsura <hk590@cam.ac.uk>
Cc: stable@vger.kernel.org
Signed-off-by: Fuad Tabba <fuad.tabba@linux.dev>
---
 arch/arm64/kvm/hyp/nvhe/setup.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/arch/arm64/kvm/hyp/nvhe/setup.c b/arch/arm64/kvm/hyp/nvhe/setup.c
index 75b00c3233102..362f2891cb32e 100644
--- a/arch/arm64/kvm/hyp/nvhe/setup.c
+++ b/arch/arm64/kvm/hyp/nvhe/setup.c
@@ -269,6 +269,16 @@ static int fix_host_ownership(void)
 			return ret;
 	}
 
+	/* The stacks sit in the private VA range, not the linear map. */
+	for (i = 0; i < hyp_nr_cpus; i++) {
+		struct kvm_nvhe_init_params *params = per_cpu_ptr(&kvm_init_params, i);
+		u64 start = params->stack_hyp_va - NVHE_STACK_SIZE;
+
+		ret = kvm_pgtable_walk(&pkvm_pgtable, start, NVHE_STACK_SIZE, &walker);
+		if (ret)
+			return ret;
+	}
+
 	return 0;
 }
 
-- 
2.39.5