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Enable hypervisor on pKVM builds

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gs101 builds are getting experimental support for pKVM which can be
enabled either using fastboot or with misc_writer. For _pkvm builds we
want the device to automatically enable pKVM for testing. This patch
adds a new early-init service which checks for the presence of /dev/kvm
and if not found, writes to /misc and forces a reboot.

Bug: 192819132
Bug: 202484976
Test: flash a _pkvm build, observe double-reboot, check /dev/kvm exists
Change-Id: I3834b3e4c6118b3f6e4093ce52d5b94117eca29c
This commit is contained in:
David Brazdil 2021-10-06 10:27:00 +00:00
parent d6bde6c1ce
commit c439f780ee
4 changed files with 112 additions and 0 deletions
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75
pkvm/pkvm_enabler.c Normal file
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/*
* Copyright (C) 2021 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#define LOG_TAG "pkvm_enabler"
#include <errno.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <log/log.h>
#define KVM_DEVICE "/dev/kvm"
#define MISC_WRITER "/vendor/bin/misc_writer"
int main() {
char *newargv[] = { MISC_WRITER, "--set-enable-pkvm", NULL };
char *newenvp[] = { NULL };
pid_t pid;
int ret, wstatus;
/* Check whether KVM device exists. */
ret = access(KVM_DEVICE, F_OK);
/* If KVM device exists, return SUCCESS to continue booting. */
if (ret == 0) {
exit(EXIT_SUCCESS);
}
if (ret != -ENOENT) {
ALOGW("Unexpected error from access(): %d", ret);
}
/*
* If KVM device does not exist, run misc_writer and return FAILURE
* to force a reboot.
*/
pid = fork();
if (pid == -1) {
ALOGE("Could not fork: %d", errno);
exit(EXIT_FAILURE);
}
if (pid == 0) {
execve(MISC_WRITER, newargv, newenvp);
ALOGE("Could not execute " MISC_WRITER ": %d", errno);
_exit(EXIT_FAILURE);
}
waitpid(pid, &wstatus, 0);
if (WIFEXITED(wstatus)) {
ret = WEXITSTATUS(wstatus);
if (ret) {
ALOGE(MISC_WRITER " exit status: %d", ret);
}
} else {
ALOGE(MISC_WRITER " terminated unexpectedly: %d", wstatus);
}
exit(EXIT_FAILURE);
}