Commit 45e4755c authored by Sean Christopherson's avatar Sean Christopherson
Browse files

KVM: selftests: Add helpers to read integer module params 



Add helpers to read integer module params, which is painfully non-trivial
because the pain of dealing with strings in C is exacerbated by the kernel
inserting a newline.

Don't bother differentiating between int, uint, short, etc.  They all fit
in an int, and KVM (thankfully) doesn't have any integer params larger
than an int.

Tested-by: default avatarDapeng Mi <dapeng1.mi@linux.intel.com>
Link: https://lore.kernel.org/r/20240109230250.424295-24-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent c85e9867

tools/testing/selftests/kvm/include/kvm_util_base.h

+4 −0
Original line number Diff line number Diff line
@@ -259,6 +259,10 @@ bool get_kvm_param_bool(const char *param); 
bool get_kvm_intel_param_bool(const char *param);

bool get_kvm_amd_param_bool(const char *param);



int get_kvm_param_integer(const char *param);

int get_kvm_intel_param_integer(const char *param);

int get_kvm_amd_param_integer(const char *param);



unsigned int kvm_check_cap(long cap);



static inline bool kvm_has_cap(long cap)

tools/testing/selftests/kvm/lib/kvm_util.c

+56 −6
Original line number Diff line number Diff line
@@ -51,13 +51,13 @@ int open_kvm_dev_path_or_exit(void) 
	return _open_kvm_dev_path_or_exit(O_RDONLY);

}



static bool get_module_param_bool(const char *module_name, const char *param)

static ssize_t get_module_param(const char *module_name, const char *param,

				void *buffer, size_t buffer_size)

{

	const int path_size = 128;

	char path[path_size];

	char value;

	ssize_t r;

	int fd;

	ssize_t bytes_read;

	int fd, r;



	r = snprintf(path, path_size, "/sys/module/%s/parameters/%s",

		     module_name, param);
@@ -66,11 +66,46 @@ static bool get_module_param_bool(const char *module_name, const char *param) 


	fd = open_path_or_exit(path, O_RDONLY);



	r = read(fd, &value, 1);

	TEST_ASSERT(r == 1, "read(%s) failed", path);

	bytes_read = read(fd, buffer, buffer_size);

	TEST_ASSERT(bytes_read > 0, "read(%s) returned %ld, wanted %ld bytes",

		    path, bytes_read, buffer_size);



	r = close(fd);

	TEST_ASSERT(!r, "close(%s) failed", path);

	return bytes_read;

}



static int get_module_param_integer(const char *module_name, const char *param)

{

	/*

	 * 16 bytes to hold a 64-bit value (1 byte per char), 1 byte for the

	 * NUL char, and 1 byte because the kernel sucks and inserts a newline

	 * at the end.

	 */

	char value[16 + 1 + 1];

	ssize_t r;



	memset(value, '\0', sizeof(value));



	r = get_module_param(module_name, param, value, sizeof(value));

	TEST_ASSERT(value[r - 1] == '\n',

		    "Expected trailing newline, got char '%c'", value[r - 1]);



	/*

	 * Squash the newline, otherwise atoi_paranoid() will complain about

	 * trailing non-NUL characters in the string.

	 */

	value[r - 1] = '\0';

	return atoi_paranoid(value);

}



static bool get_module_param_bool(const char *module_name, const char *param)

{

	char value;

	ssize_t r;



	r = get_module_param(module_name, param, &value, sizeof(value));

	TEST_ASSERT_EQ(r, 1);



	if (value == 'Y')

		return true;
@@ -95,6 +130,21 @@ bool get_kvm_amd_param_bool(const char *param) 
	return get_module_param_bool("kvm_amd", param);

}



int get_kvm_param_integer(const char *param)

{

	return get_module_param_integer("kvm", param);

}



int get_kvm_intel_param_integer(const char *param)

{

	return get_module_param_integer("kvm_intel", param);

}



int get_kvm_amd_param_integer(const char *param)

{

	return get_module_param_integer("kvm_amd", param);

}



/*

 * Capability

 *