KVM: arm64: Introduce __pkvm_host_wrprotect_guest()

Introduce a new hypercall to remove the write permission from a
non-protected guest stage-2 mapping. This will be used for e.g. enabling
dirty logging.

Tested-by: Fuad Tabba <tabba@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20241218194059.3670226-14-qperret@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>

diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index 66ee8542dcc9d740a45c117066496677d6d47ea9..8663a588cf34ac331d9262523919875c73cc584d 100644 (file)
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -68,6 +68,7 @@ enum __kvm_host_smccc_func {
        __KVM_HOST_SMCCC_FUNC___pkvm_host_share_guest,
        __KVM_HOST_SMCCC_FUNC___pkvm_host_unshare_guest,
        __KVM_HOST_SMCCC_FUNC___pkvm_host_relax_perms_guest,
+       __KVM_HOST_SMCCC_FUNC___pkvm_host_wrprotect_guest,
        __KVM_HOST_SMCCC_FUNC___kvm_adjust_pc,
        __KVM_HOST_SMCCC_FUNC___kvm_vcpu_run,
        __KVM_HOST_SMCCC_FUNC___kvm_flush_vm_context,

diff --git a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
index 181aec2d5bc1a1b8e2b155c20eb12f43ef31c72b..0bbfb0e1734cd28d8fb49b0693232d375561d636 100644 (file)
--- a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
@@ -43,6 +43,7 @@ int __pkvm_host_share_guest(u64 pfn, u64 gfn, struct pkvm_hyp_vcpu *vcpu,
                            enum kvm_pgtable_prot prot);
 int __pkvm_host_unshare_guest(u64 gfn, struct pkvm_hyp_vm *hyp_vm);
 int __pkvm_host_relax_perms_guest(u64 gfn, struct pkvm_hyp_vcpu *vcpu, enum kvm_pgtable_prot prot);
+int __pkvm_host_wrprotect_guest(u64 gfn, struct pkvm_hyp_vm *hyp_vm);
 
 bool addr_is_memory(phys_addr_t phys);
 int host_stage2_idmap_locked(phys_addr_t addr, u64 size, enum kvm_pgtable_prot prot);

diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index 287e4ee93ef2198bd6389bb08d29bee50e0c73fa..98d3177351073d18d98193adbf12aad57e5b64d3 100644 (file)
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -283,6 +283,26 @@ out:
        cpu_reg(host_ctxt, 1) = ret;
 }
 
+static void handle___pkvm_host_wrprotect_guest(struct kvm_cpu_context *host_ctxt)
+{
+       DECLARE_REG(pkvm_handle_t, handle, host_ctxt, 1);
+       DECLARE_REG(u64, gfn, host_ctxt, 2);
+       struct pkvm_hyp_vm *hyp_vm;
+       int ret = -EINVAL;
+
+       if (!is_protected_kvm_enabled())
+               goto out;
+
+       hyp_vm = get_np_pkvm_hyp_vm(handle);
+       if (!hyp_vm)
+               goto out;
+
+       ret = __pkvm_host_wrprotect_guest(gfn, hyp_vm);
+       put_pkvm_hyp_vm(hyp_vm);
+out:
+       cpu_reg(host_ctxt, 1) = ret;
+}
+
 static void handle___kvm_adjust_pc(struct kvm_cpu_context *host_ctxt)
 {
        DECLARE_REG(struct kvm_vcpu *, vcpu, host_ctxt, 1);
@@ -495,6 +515,7 @@ static const hcall_t host_hcall[] = {
        HANDLE_FUNC(__pkvm_host_share_guest),
        HANDLE_FUNC(__pkvm_host_unshare_guest),
        HANDLE_FUNC(__pkvm_host_relax_perms_guest),
+       HANDLE_FUNC(__pkvm_host_wrprotect_guest),
        HANDLE_FUNC(__kvm_adjust_pc),
        HANDLE_FUNC(__kvm_vcpu_run),
        HANDLE_FUNC(__kvm_flush_vm_context),

diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index aa8e0408aebb564a2a8e928b7c7028069b5f2374..94e4251b5077863cdf1c95c54510780f80a8243e 100644 (file)
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -1511,3 +1511,22 @@ int __pkvm_host_relax_perms_guest(u64 gfn, struct pkvm_hyp_vcpu *vcpu, enum kvm_
 
        return ret;
 }
+
+int __pkvm_host_wrprotect_guest(u64 gfn, struct pkvm_hyp_vm *vm)
+{
+       u64 ipa = hyp_pfn_to_phys(gfn);
+       u64 phys;
+       int ret;
+
+       host_lock_component();
+       guest_lock_component(vm);
+
+       ret = __check_host_shared_guest(vm, &phys, ipa);
+       if (!ret)
+               ret = kvm_pgtable_stage2_wrprotect(&vm->pgt, ipa, PAGE_SIZE);
+
+       guest_unlock_component(vm);
+       host_unlock_component();
+
+       return ret;
+}