[PATCH v2 02/13] KVM: arm64: Track host-unmapped MMIO regions in a static array

[Sebastian Ene]

Introduce a registry to track protected MMIO regions that are unmapped
from the host stage-2 page tables. These regions are stored in a
fixed-size array and their ownership is donated to the hypervisor during
initialization to ensure host-exclusion and persistent tracking.

Signed-off-by: Sebastian Ene <sebastianene at google.com>
---
 arch/arm64/include/asm/kvm_pkvm.h     | 11 +++++++++++
 arch/arm64/kvm/hyp/nvhe/mem_protect.c |  3 +++
 arch/arm64/kvm/hyp/nvhe/setup.c       | 24 ++++++++++++++++++++++++
 3 files changed, 38 insertions(+)

diff --git a/arch/arm64/include/asm/kvm_pkvm.h b/arch/arm64/include/asm/kvm_pkvm.h
index 74fedd9c5ff0..ab26bec079d6 100644
--- a/arch/arm64/include/asm/kvm_pkvm.h
+++ b/arch/arm64/include/asm/kvm_pkvm.h
@@ -17,6 +17,17 @@
 
 #define HYP_MEMBLOCK_REGIONS 128
 
+/* The maximum number of hypervisor protected regions from the host */
+#define PKVM_PROTECTED_REGS_NUM	8
+
+struct pkvm_protected_reg {
+	u64 pfn;
+	u64 nr_pages;
+};
+
+extern struct pkvm_protected_reg kvm_nvhe_sym(pkvm_protected_regs)[];
+extern unsigned int kvm_nvhe_sym(num_protected_reg);
+
 int pkvm_init_host_vm(struct kvm *kvm, unsigned long type);
 int pkvm_create_hyp_vm(struct kvm *kvm);
 bool pkvm_hyp_vm_is_created(struct kvm *kvm);
diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index 5cf7c4a0ed20..500c18c2fd48 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -28,6 +28,9 @@ struct host_mmu host_mmu;
 
 static struct hyp_pool host_s2_pool;
 
+unsigned int num_protected_reg;
+struct pkvm_protected_reg pkvm_protected_regs[PKVM_PROTECTED_REGS_NUM];
+
 static DEFINE_PER_CPU(struct pkvm_hyp_vm *, __current_vm);
 #define current_vm (*this_cpu_ptr(&__current_vm))
 
diff --git a/arch/arm64/kvm/hyp/nvhe/setup.c b/arch/arm64/kvm/hyp/nvhe/setup.c
index 75b00c323310..64c0290da888 100644
--- a/arch/arm64/kvm/hyp/nvhe/setup.c
+++ b/arch/arm64/kvm/hyp/nvhe/setup.c
@@ -284,6 +284,26 @@ static int fix_hyp_pgtable_refcnt(void)
 				&walker);
 }
 
+static int donate_protected_mmio_regions(void)
+{
+	int ret;
+	int i;
+
+	for (i = 0; i < num_protected_reg; i++) {
+		ret = __pkvm_host_donate_hyp_mmio(hyp_pfn_to_phys(pkvm_protected_regs[i].pfn),
+						  pkvm_protected_regs[i].nr_pages << PAGE_SHIFT);
+		if (ret)
+			goto err_setup;
+	}
+
+	return 0;
+err_setup:
+	while (--i >= 0)
+		__pkvm_hyp_donate_host_mmio(hyp_pfn_to_phys(pkvm_protected_regs[i].pfn),
+					    pkvm_protected_regs[i].nr_pages << PAGE_SHIFT);
+	return ret;
+}
+
 void __noreturn __pkvm_init_finalise(void)
 {
 	struct kvm_cpu_context *host_ctxt = host_data_ptr(host_ctxt);
@@ -324,6 +344,10 @@ void __noreturn __pkvm_init_finalise(void)
 	if (ret)
 		goto out;
 
+	ret = donate_protected_mmio_regions();
+	if (ret)
+		goto out;
+
 	ret = hyp_ffa_init(ffa_proxy_pages);
 	if (ret)
 		goto out;
-- 
2.55.0.654.g21b8a5bc05-goog