KVM: selftests: Automatically do init_ucall() for non-barebones VMs

Do init_ucall() automatically during VM creation to kill two (three?)
birds with one stone.

First, initializing ucall immediately after VM creations allows forcing
aarch64's MMIO ucall address to immediately follow memslot0.  This is
still somewhat fragile as tests could clobber the MMIO address with a
new memslot, but it's safe-ish since tests have to be conversative when
accounting for memslot0.  And this can be hardened in the future by
creating a read-only memslot for the MMIO page (KVM ARM exits with MMIO
if the guest writes to a read-only memslot).  Add a TODO to document that
selftests can and should use a memslot for the ucall MMIO (doing so
requires yet more rework because tests assumes thay can use all memslots
except memslot0).

Second, initializing ucall for all VMs prepares for making ucall
initialization meaningful on all architectures.  aarch64 is currently the
only arch that needs to do any setup, but that will change in the future
by switching to a pool-based implementation (instead of the current
stack-based approach).

Lastly, defining the ucall MMIO address from common code will simplify
switching all architectures (except s390) to a common MMIO-based ucall
implementation (if there's ever sufficient motivation to do so).

Cc: Oliver Upton <oliver.upton@linux.dev>
Reviewed-by: Andrew Jones <andrew.jones@linux.dev>
Tested-by: Peter Gonda <pgonda@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221006003409.649993-4-seanjc@google.com

diff --git a/tools/testing/selftests/kvm/aarch64/aarch32_id_regs.c b/tools/testing/selftests/kvm/aarch64/aarch32_id_regs.c
index 6f9c1f1..03f6b3a 100644 (file)
--- a/tools/testing/selftests/kvm/aarch64/aarch32_id_regs.c
+++ b/tools/testing/selftests/kvm/aarch64/aarch32_id_regs.c
@@ -158,8 +158,6 @@ int main(void)
 
        TEST_REQUIRE(vcpu_aarch64_only(vcpu));
 
-       ucall_init(vm, NULL);
-
        test_user_raz_wi(vcpu);
        test_user_raz_invariant(vcpu);
        test_guest_raz(vcpu);

diff --git a/tools/testing/selftests/kvm/aarch64/arch_timer.c b/tools/testing/selftests/kvm/aarch64/arch_timer.c
index 9409617..54016cd 100644 (file)
--- a/tools/testing/selftests/kvm/aarch64/arch_timer.c
+++ b/tools/testing/selftests/kvm/aarch64/arch_timer.c
@@ -375,7 +375,6 @@ static struct kvm_vm *test_vm_create(void)
        for (i = 0; i < nr_vcpus; i++)
                vcpu_init_descriptor_tables(vcpus[i]);
 
-       ucall_init(vm, NULL);
        test_init_timer_irq(vm);
        gic_fd = vgic_v3_setup(vm, nr_vcpus, 64, GICD_BASE_GPA, GICR_BASE_GPA);
        __TEST_REQUIRE(gic_fd >= 0, "Failed to create vgic-v3");

diff --git a/tools/testing/selftests/kvm/aarch64/debug-exceptions.c b/tools/testing/selftests/kvm/aarch64/debug-exceptions.c
index a3c2216..d86c4e4 100644 (file)
--- a/tools/testing/selftests/kvm/aarch64/debug-exceptions.c
+++ b/tools/testing/selftests/kvm/aarch64/debug-exceptions.c
@@ -292,7 +292,6 @@ static void test_guest_debug_exceptions(void)
        int stage;
 
        vm = vm_create_with_one_vcpu(&vcpu, guest_code);
-       ucall_init(vm, NULL);
 
        vm_init_descriptor_tables(vm);
        vcpu_init_descriptor_tables(vcpu);
@@ -343,7 +342,6 @@ void test_single_step_from_userspace(int test_cnt)
        struct kvm_guest_debug debug = {};
 
        vm = vm_create_with_one_vcpu(&vcpu, guest_code_ss);
-       ucall_init(vm, NULL);
        run = vcpu->run;
        vcpu_args_set(vcpu, 1, test_cnt);
 

diff --git a/tools/testing/selftests/kvm/aarch64/hypercalls.c b/tools/testing/selftests/kvm/aarch64/hypercalls.c
index a39da3f..3dceecf 100644 (file)
--- a/tools/testing/selftests/kvm/aarch64/hypercalls.c
+++ b/tools/testing/selftests/kvm/aarch64/hypercalls.c
@@ -236,7 +236,6 @@ static struct kvm_vm *test_vm_create(struct kvm_vcpu **vcpu)
 
        vm = vm_create_with_one_vcpu(vcpu, guest_code);
 
-       ucall_init(vm, NULL);
        steal_time_init(*vcpu);
 
        return vm;

diff --git a/tools/testing/selftests/kvm/aarch64/psci_test.c b/tools/testing/selftests/kvm/aarch64/psci_test.c
index e0b9e81..cfa36f3 100644 (file)
--- a/tools/testing/selftests/kvm/aarch64/psci_test.c
+++ b/tools/testing/selftests/kvm/aarch64/psci_test.c
@@ -79,7 +79,6 @@ static struct kvm_vm *setup_vm(void *guest_code, struct kvm_vcpu **source,
        struct kvm_vm *vm;
 
        vm = vm_create(2);
-       ucall_init(vm, NULL);
 
        vm_ioctl(vm, KVM_ARM_PREFERRED_TARGET, &init);
        init.features[0] |= (1 << KVM_ARM_VCPU_PSCI_0_2);

diff --git a/tools/testing/selftests/kvm/aarch64/vgic_init.c b/tools/testing/selftests/kvm/aarch64/vgic_init.c
index 9c131d9..eef816b 100644 (file)
--- a/tools/testing/selftests/kvm/aarch64/vgic_init.c
+++ b/tools/testing/selftests/kvm/aarch64/vgic_init.c
@@ -68,8 +68,6 @@ static void guest_code(void)
 /* we don't want to assert on run execution, hence that helper */
 static int run_vcpu(struct kvm_vcpu *vcpu)
 {
-       ucall_init(vcpu->vm, NULL);
-
        return __vcpu_run(vcpu) ? -errno : 0;
 }
 

diff --git a/tools/testing/selftests/kvm/aarch64/vgic_irq.c b/tools/testing/selftests/kvm/aarch64/vgic_irq.c
index 4ead42a..e0310eb 100644 (file)
--- a/tools/testing/selftests/kvm/aarch64/vgic_irq.c
+++ b/tools/testing/selftests/kvm/aarch64/vgic_irq.c
@@ -756,7 +756,6 @@ static void test_vgic(uint32_t nr_irqs, bool level_sensitive, bool eoi_split)
        print_args(&args);
 
        vm = vm_create_with_one_vcpu(&vcpu, guest_code);
-       ucall_init(vm, NULL);
 
        vm_init_descriptor_tables(vm);
        vcpu_init_descriptor_tables(vcpu);

diff --git a/tools/testing/selftests/kvm/dirty_log_test.c b/tools/testing/selftests/kvm/dirty_log_test.c
index b5234d6..b458a27 100644 (file)
--- a/tools/testing/selftests/kvm/dirty_log_test.c
+++ b/tools/testing/selftests/kvm/dirty_log_test.c
@@ -756,8 +756,6 @@ static void run_test(enum vm_guest_mode mode, void *arg)
        /* Cache the HVA pointer of the region */
        host_test_mem = addr_gpa2hva(vm, (vm_paddr_t)guest_test_phys_mem);
 
-       ucall_init(vm, NULL);
-
        /* Export the shared variables to the guest */
        sync_global_to_guest(vm, host_page_size);
        sync_global_to_guest(vm, guest_page_size);

diff --git a/tools/testing/selftests/kvm/include/ucall_common.h b/tools/testing/selftests/kvm/include/ucall_common.h
index 63bfc60..8077a6d 100644 (file)
--- a/tools/testing/selftests/kvm/include/ucall_common.h
+++ b/tools/testing/selftests/kvm/include/ucall_common.h
@@ -24,7 +24,7 @@ struct ucall {
        uint64_t args[UCALL_MAX_ARGS];
 };
 
-void ucall_arch_init(struct kvm_vm *vm, void *arg);
+void ucall_arch_init(struct kvm_vm *vm, vm_paddr_t mmio_gpa);
 void ucall_arch_uninit(struct kvm_vm *vm);
 void ucall_arch_do_ucall(vm_vaddr_t uc);
 void *ucall_arch_get_ucall(struct kvm_vcpu *vcpu);
@@ -32,9 +32,9 @@ void *ucall_arch_get_ucall(struct kvm_vcpu *vcpu);
 void ucall(uint64_t cmd, int nargs, ...);
 uint64_t get_ucall(struct kvm_vcpu *vcpu, struct ucall *uc);
 
-static inline void ucall_init(struct kvm_vm *vm, void *arg)
+static inline void ucall_init(struct kvm_vm *vm, vm_paddr_t mmio_gpa)
 {
-       ucall_arch_init(vm, arg);
+       ucall_arch_init(vm, mmio_gpa);
 }
 
 static inline void ucall_uninit(struct kvm_vm *vm)

diff --git a/tools/testing/selftests/kvm/kvm_page_table_test.c b/tools/testing/selftests/kvm/kvm_page_table_test.c
index 696b366..3db32d5 100644 (file)
--- a/tools/testing/selftests/kvm/kvm_page_table_test.c
+++ b/tools/testing/selftests/kvm/kvm_page_table_test.c
@@ -289,7 +289,6 @@ static struct kvm_vm *pre_init_before_test(enum vm_guest_mode mode, void *arg)
        host_test_mem = addr_gpa2hva(vm, (vm_paddr_t)guest_test_phys_mem);
 
        /* Export shared structure test_args to guest */
-       ucall_init(vm, NULL);
        sync_global_to_guest(vm, test_args);
 
        ret = sem_init(&test_stage_updated, 0, 0);

diff --git a/tools/testing/selftests/kvm/lib/aarch64/ucall.c b/tools/testing/selftests/kvm/lib/aarch64/ucall.c
index f214f5c..f02ae27 100644 (file)
--- a/tools/testing/selftests/kvm/lib/aarch64/ucall.c
+++ b/tools/testing/selftests/kvm/lib/aarch64/ucall.c
@@ -8,60 +8,12 @@
 
 static vm_vaddr_t *ucall_exit_mmio_addr;
 
-static bool ucall_mmio_init(struct kvm_vm *vm, vm_paddr_t gpa)
+void ucall_arch_init(struct kvm_vm *vm, vm_paddr_t mmio_gpa)
 {
-       if (kvm_userspace_memory_region_find(vm, gpa, gpa + 1))
-               return false;
+       virt_pg_map(vm, mmio_gpa, mmio_gpa);
 
-       virt_pg_map(vm, gpa, gpa);
-
-       ucall_exit_mmio_addr = (vm_vaddr_t *)gpa;
+       ucall_exit_mmio_addr = (vm_vaddr_t *)mmio_gpa;
        sync_global_to_guest(vm, ucall_exit_mmio_addr);
-
-       return true;
-}
-
-void ucall_arch_init(struct kvm_vm *vm, void *arg)
-{
-       vm_paddr_t gpa, start, end, step, offset;
-       unsigned int bits;
-       bool ret;
-
-       if (arg) {
-               gpa = (vm_paddr_t)arg;
-               ret = ucall_mmio_init(vm, gpa);
-               TEST_ASSERT(ret, "Can't set ucall mmio address to %lx", gpa);
-               return;
-       }
-
-       /*
-        * Find an address within the allowed physical and virtual address
-        * spaces, that does _not_ have a KVM memory region associated with
-        * it. Identity mapping an address like this allows the guest to
-        * access it, but as KVM doesn't know what to do with it, it
-        * will assume it's something userspace handles and exit with
-        * KVM_EXIT_MMIO. Well, at least that's how it works for AArch64.
-        * Here we start with a guess that the addresses around 5/8th
-        * of the allowed space are unmapped and then work both down and
-        * up from there in 1/16th allowed space sized steps.
-        *
-        * Note, we need to use VA-bits - 1 when calculating the allowed
-        * virtual address space for an identity mapping because the upper
-        * half of the virtual address space is the two's complement of the
-        * lower and won't match physical addresses.
-        */
-       bits = vm->va_bits - 1;
-       bits = min(vm->pa_bits, bits);
-       end = 1ul << bits;
-       start = end * 5 / 8;
-       step = end / 16;
-       for (offset = 0; offset < end - start; offset += step) {
-               if (ucall_mmio_init(vm, start - offset))
-                       return;
-               if (ucall_mmio_init(vm, start + offset))
-                       return;
-       }
-       TEST_FAIL("Can't find a ucall mmio address");
 }
 
 void ucall_arch_uninit(struct kvm_vm *vm)

diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index 3b7710f..07c8edd 100644 (file)
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -335,15 +335,26 @@ struct kvm_vm *__vm_create(enum vm_guest_mode mode, uint32_t nr_runnable_vcpus,
 {
        uint64_t nr_pages = vm_nr_pages_required(mode, nr_runnable_vcpus,
                                                 nr_extra_pages);
+       struct userspace_mem_region *slot0;
        struct kvm_vm *vm;
 
        vm = ____vm_create(mode, nr_pages);
 
        kvm_vm_elf_load(vm, program_invocation_name);
 
+       /*
+        * TODO: Add proper defines to protect the library's memslots, and then
+        * carve out memslot1 for the ucall MMIO address.  KVM treats writes to
+        * read-only memslots as MMIO, and creating a read-only memslot for the
+        * MMIO region would prevent silently clobbering the MMIO region.
+        */
+       slot0 = memslot2region(vm, 0);
+       ucall_init(vm, slot0->region.guest_phys_addr + slot0->region.memory_size);
+
 #ifdef __x86_64__
        vm_create_irqchip(vm);
 #endif
+
        return vm;
 }
 

diff --git a/tools/testing/selftests/kvm/lib/memstress.c b/tools/testing/selftests/kvm/lib/memstress.c
index 503da78..b66404e 100644 (file)
--- a/tools/testing/selftests/kvm/lib/memstress.c
+++ b/tools/testing/selftests/kvm/lib/memstress.c
@@ -221,8 +221,6 @@ struct kvm_vm *memstress_create_vm(enum vm_guest_mode mode, int nr_vcpus,
                memstress_setup_nested(vm, nr_vcpus, vcpus);
        }
 
-       ucall_init(vm, NULL);
-
        /* Export the shared variables to the guest. */
        sync_global_to_guest(vm, memstress_args);
 

diff --git a/tools/testing/selftests/kvm/lib/riscv/ucall.c b/tools/testing/selftests/kvm/lib/riscv/ucall.c
index 37e091d..c58ecb8 100644 (file)
--- a/tools/testing/selftests/kvm/lib/riscv/ucall.c
+++ b/tools/testing/selftests/kvm/lib/riscv/ucall.c
@@ -10,7 +10,7 @@
 #include "kvm_util.h"
 #include "processor.h"
 
-void ucall_arch_init(struct kvm_vm *vm, void *arg)
+void ucall_arch_init(struct kvm_vm *vm, vm_paddr_t mmio_gpa)
 {
 }
 

diff --git a/tools/testing/selftests/kvm/lib/s390x/ucall.c b/tools/testing/selftests/kvm/lib/s390x/ucall.c
index 0f695a0..208f0f0 100644 (file)
--- a/tools/testing/selftests/kvm/lib/s390x/ucall.c
+++ b/tools/testing/selftests/kvm/lib/s390x/ucall.c
@@ -6,7 +6,7 @@
  */
 #include "kvm_util.h"
 
-void ucall_arch_init(struct kvm_vm *vm, void *arg)
+void ucall_arch_init(struct kvm_vm *vm, vm_paddr_t mmio_gpa)
 {
 }
 

diff --git a/tools/testing/selftests/kvm/lib/x86_64/ucall.c b/tools/testing/selftests/kvm/lib/x86_64/ucall.c
index ead9946..016a048 100644 (file)
--- a/tools/testing/selftests/kvm/lib/x86_64/ucall.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/ucall.c
@@ -8,7 +8,7 @@
 
 #define UCALL_PIO_PORT ((uint16_t)0x1000)
 
-void ucall_arch_init(struct kvm_vm *vm, void *arg)
+void ucall_arch_init(struct kvm_vm *vm, vm_paddr_t mmio_gpa)
 {
 }
 

diff --git a/tools/testing/selftests/kvm/memslot_perf_test.c b/tools/testing/selftests/kvm/memslot_perf_test.c
index 330aaef..d771262 100644 (file)
--- a/tools/testing/selftests/kvm/memslot_perf_test.c
+++ b/tools/testing/selftests/kvm/memslot_perf_test.c
@@ -277,7 +277,6 @@ static bool prepare_vm(struct vm_data *data, int nslots, uint64_t *maxslots,
        TEST_ASSERT(data->hva_slots, "malloc() fail");
 
        data->vm = __vm_create_with_one_vcpu(&data->vcpu, mempages, guest_code);
-       ucall_init(data->vm, NULL);
 
        pr_info_v("Adding slots 1..%i, each slot with %"PRIu64" pages + %"PRIu64" extra pages last\n",
                max_mem_slots - 1, data->pages_per_slot, rempages);

diff --git a/tools/testing/selftests/kvm/rseq_test.c b/tools/testing/selftests/kvm/rseq_test.c
index 6f88da7..0e9e2b4 100644 (file)
--- a/tools/testing/selftests/kvm/rseq_test.c
+++ b/tools/testing/selftests/kvm/rseq_test.c
@@ -224,7 +224,6 @@ int main(int argc, char *argv[])
         * CPU affinity.
         */
        vm = vm_create_with_one_vcpu(&vcpu, guest_code);
-       ucall_init(vm, NULL);
 
        pthread_create(&migration_thread, NULL, migration_worker,
                       (void *)(unsigned long)syscall(SYS_gettid));

diff --git a/tools/testing/selftests/kvm/steal_time.c b/tools/testing/selftests/kvm/steal_time.c
index db8967f..c87f387 100644 (file)
--- a/tools/testing/selftests/kvm/steal_time.c
+++ b/tools/testing/selftests/kvm/steal_time.c
@@ -266,7 +266,6 @@ int main(int ac, char **av)
        gpages = vm_calc_num_guest_pages(VM_MODE_DEFAULT, STEAL_TIME_SIZE * NR_VCPUS);
        vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS, ST_GPA_BASE, 1, gpages, 0);
        virt_map(vm, ST_GPA_BASE, ST_GPA_BASE, gpages);
-       ucall_init(vm, NULL);
 
        TEST_REQUIRE(is_steal_time_supported(vcpus[0]));
 

diff --git a/tools/testing/selftests/kvm/system_counter_offset_test.c b/tools/testing/selftests/kvm/system_counter_offset_test.c
index 1c27493..7f5b330 100644 (file)
--- a/tools/testing/selftests/kvm/system_counter_offset_test.c
+++ b/tools/testing/selftests/kvm/system_counter_offset_test.c
@@ -121,7 +121,6 @@ int main(void)
 
        vm = vm_create_with_one_vcpu(&vcpu, guest_main);
        check_preconditions(vcpu);
-       ucall_init(vm, NULL);
 
        enter_guest(vcpu);
        kvm_vm_free(vm);