[PATCH 02/14] KVM: arm64: Track host-unmapped MMIO regions in a static array

Sebastian Ene
2026-03-10T12:49:58Z

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@google.com>
---
arch/arm64/include/asm/kvm_pkvm.h | 10 ++++++++++
arch/arm64/kvm/hyp/nvhe/mem_protect.c | 3 +++
arch/arm64/kvm/hyp/nvhe/setup.c | 25 +++++++++++++++++++++++++
3 files changed, 38 insertions(+)

diff --git a/arch/arm64/include/asm/kvm_pkvm.h b/arch/arm64/include/asm/kvm_pkvm.h
index 757076ad4ec9..48ec7d519399 100644
--- a/arch/arm64/include/asm/kvm_pkvm.h
+++ b/arch/arm64/include/asm/kvm_pkvm.h
@@ -17,6 +17,16 @@

#define HYP_MEMBLOCK_REGIONS 128

+#define PKVM_PROTECTED_REGS_NUM 8
+
+struct pkvm_protected_reg {
+ u64 start_pfn;
+ size_t num_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);
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 0808367c52e5..7c125836b533 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -23,6 +23,9 @@

struct host_mmu host_mmu;

+struct pkvm_protected_reg pkvm_protected_regs[PKVM_PROTECTED_REGS_NUM];
+unsigned int num_protected_reg;
+
static struct hyp_pool host_s2_pool;

static DEFINE_PER_CPU(struct pkvm_hyp_vm *, __current_vm);
diff --git a/arch/arm64/kvm/hyp/nvhe/setup.c b/arch/arm64/kvm/hyp/nvhe/setup.c
index 90bd014e952f..ad5b96085e1b 100644
--- a/arch/arm64/kvm/hyp/nvhe/setup.c
+++ b/arch/arm64/kvm/hyp/nvhe/setup.c
@@ -284,6 +284,27 @@ static int fix_hyp_pgtable_refcnt(void)
&walker);
}

+static int unmap_protected_regions(void)
+{
+ struct pkvm_protected_reg *reg;
+ int i, ret, j = 0;
+
+ for (i = 0; i < num_protected_reg; i++) {
+ reg = &pkvm_protected_regs[i];
+ for (j = 0; j < reg->num_pages; j++) {
+ ret = __pkvm_host_donate_hyp_mmio(reg->start_pfn + j);
+ if (ret)
+ goto err_setup;
+ }
+ }
+
+ return 0;
+err_setup:
+ for (j = j - 1; j >= 0; j--)
+ __pkvm_hyp_donate_host_mmio(reg->start_pfn + j);
+ return ret;
+}
+
void __noreturn __pkvm_init_finalise(void)
{
struct kvm_cpu_context *host_ctxt = host_data_ptr(host_ctxt);
@@ -324,6 +345,10 @@ void __noreturn __pkvm_init_finalise(void)
if (ret)
goto out;

+ ret = unmap_protected_regions();
+ if (ret)
+ goto out;
+
ret = hyp_ffa_init(ffa_proxy_pages);
if (ret)
goto out;
--
2.53.0.473.g4a7958ca14-goog