[16/16] arm64: Register earlycon fixmap with the MMIO guard

Commit Message

Marc Zyngier July 15, 2021, 4:31 p.m. UTC

On initialising the MMIO guard infrastructure, register the
earlycon mapping if present.

Signed-off-by: Marc Zyngier <[e-mail]>
---
 arch/arm64/mm/ioremap.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

Patch

diff --git a/arch/arm64/mm/ioremap.c b/arch/arm64/mm/ioremap.c
index d82b63bcc554..a27b58e03c93 100644
--- a/arch/arm64/mm/ioremap.c
+++ b/arch/arm64/mm/ioremap.c
@@ -32,6 +32,18 @@  static int __init ioremap_guard_setup(char *str)
 }
 early_param("ioremap_guard", ioremap_guard_setup);
 
+static void fixup_fixmap(void)
+{
+	unsigned long addr = __fix_to_virt(FIX_EARLYCON_MEM_BASE);
+	pte_t *ptep = __get_fixmap_pte(FIX_EARLYCON_MEM_BASE);
+
+	if (!ptep)
+		return;
+
+	ioremap_page_range_hook(addr, addr + PAGE_SIZE, __pte_to_phys(*ptep),
+				__pgprot(pte_val(*ptep) & PTE_ATTRINDX_MASK));
+}
+
 void kvm_init_ioremap_services(void)
 {
 	struct arm_smccc_res res;
@@ -55,6 +67,7 @@  void kvm_init_ioremap_services(void)
 			     &res);
 	if (res.a0 == SMCCC_RET_SUCCESS) {
 		static_branch_enable(&ioremap_guard_key);
+		fixup_fixmap();
 		pr_info("Using KVM MMIO guard for ioremap\n");
 	} else {
 		pr_warn("KVM MMIO guard registration failed (%ld)\n", res.a0);