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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Test shared zeropage handling (with/without storage keys)
*
* Copyright (C) 2024, Red Hat, Inc.
*/
#include <sys/mman.h>
#include <linux/fs.h>
#include "test_util.h"
#include "kvm_util.h"
#include "kselftest.h"
#include "ucall_common.h"
static void set_storage_key(void *addr, uint8_t skey)
{
asm volatile("sske %0,%1" : : "d" (skey), "a" (addr));
}
static void guest_code(void)
{
/* Issue some storage key instruction. */
set_storage_key((void *)0, 0x98);
GUEST_DONE();
}
/*
* Returns 1 if the shared zeropage is mapped, 0 if something else is mapped.
* Returns < 0 on error or if nothing is mapped.
*/
static int maps_shared_zeropage(int pagemap_fd, void *addr)
{
struct page_region region;
struct pm_scan_arg arg = {
.start = (uintptr_t)addr,
.end = (uintptr_t)addr + 4096,
.vec = (uintptr_t)®ion,
.vec_len = 1,
.size = sizeof(struct pm_scan_arg),
.category_mask = PAGE_IS_PFNZERO,
.category_anyof_mask = PAGE_IS_PRESENT,
.return_mask = PAGE_IS_PFNZERO,
};
return ioctl(pagemap_fd, PAGEMAP_SCAN, &arg);
}
int main(int argc, char *argv[])
{
char *mem, *page0, *page1, *page2, tmp;
const size_t pagesize = getpagesize();
struct kvm_vcpu *vcpu;
struct kvm_vm *vm;
struct ucall uc;
int pagemap_fd;
ksft_print_header();
ksft_set_plan(3);
/*
* We'll use memory that is not mapped into the VM for simplicity.
* Shared zeropages are enabled/disabled per-process.
*/
mem = mmap(0, 3 * pagesize, PROT_READ, MAP_PRIVATE | MAP_ANON, -1, 0);
TEST_ASSERT(mem != MAP_FAILED, "mmap() failed");
/* Disable THP. Ignore errors on older kernels. */
madvise(mem, 3 * pagesize, MADV_NOHUGEPAGE);
page0 = mem;
page1 = page0 + pagesize;
page2 = page1 + pagesize;
/* Can we even detect shared zeropages? */
pagemap_fd = open("/proc/self/pagemap", O_RDONLY);
TEST_REQUIRE(pagemap_fd >= 0);
tmp = *page0;
asm volatile("" : "+r" (tmp));
TEST_REQUIRE(maps_shared_zeropage(pagemap_fd, page0) == 1);
vm = vm_create_with_one_vcpu(&vcpu, guest_code);
/* Verify that we get the shared zeropage after VM creation. */
tmp = *page1;
asm volatile("" : "+r" (tmp));
ksft_test_result(maps_shared_zeropage(pagemap_fd, page1) == 1,
"Shared zeropages should be enabled\n");
/*
* Let our VM execute a storage key instruction that should
* unshare all shared zeropages.
*/
vcpu_run(vcpu);
get_ucall(vcpu, &uc);
TEST_ASSERT_EQ(uc.cmd, UCALL_DONE);
/* Verify that we don't have a shared zeropage anymore. */
ksft_test_result(!maps_shared_zeropage(pagemap_fd, page1),
"Shared zeropage should be gone\n");
/* Verify that we don't get any new shared zeropages. */
tmp = *page2;
asm volatile("" : "+r" (tmp));
ksft_test_result(!maps_shared_zeropage(pagemap_fd, page2),
"Shared zeropages should be disabled\n");
kvm_vm_free(vm);
ksft_finished();
}
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