Allow administrators to disable host log transfer on ordinary guests or opt in on encrypted guests. Expose the boolean recording policy through kernel.vmware_record_panic_msg using proc_dobool(), as Joel suggested. Zero disables recording, nonzero integers enable it, and reads return 0 or 1.
Register the sysctl only after the logger is ready. A registration failure leaves the internal default in force. Document that the log is sent before kdump, and that disable_panic_notifiers_platform_list also skips it. Link: https://lore.kernel.org/r/4e73yd2ofpdzl6rptzvd74no3hnyfblknoq7wzxlw7f3zjbz7c@srfabx6lsusj Signed-off-by: Zack Rusin <[email protected]> --- v3: Document the platform list ordering and the disable switch, and fix the short section-title underline reported by Sashiko. No code change from v2. Documentation/admin-guide/sysctl/kernel.rst | 20 ++++++++++++++++++++ arch/x86/kernel/cpu/vmware.c | 15 +++++++++++++++ 2 files changed, 35 insertions(+) diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index 608055d7ccc4..be2d5aa52362 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -1680,6 +1680,26 @@ entry will default to 2 instead of 0. = ============================================================= +vmware_record_panic_msg +======================= + +Controls whether kmsg data is written to the host's ``vmware.log`` on +panic. This setting does not control the separate VMware guest-crash +event. Writing zero disables recording; writing a nonzero integer +enables it. Reads return 0 or 1. + += ============================================================== +0 Do not write kmsg data to ``vmware.log``. This is the default + for encrypted guests. +1 Write kmsg data to ``vmware.log``. This is the default for + ordinary guests. += ============================================================== + +The data is written by a platform panic notifier: early in panic, +before kdump, and also when a fatal oops enters kdump without a panic. +Setting ``disable_panic_notifiers_platform_list`` skips it as well. + + warn_limit ========== diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c index 0c6f7248a665..8c8b6dd7c3e8 100644 --- a/arch/x86/kernel/cpu/vmware.c +++ b/arch/x86/kernel/cpu/vmware.c @@ -33,6 +33,7 @@ #include <linux/reboot.h> #include <linux/sizes.h> #include <linux/static_call.h> +#include <linux/sysctl.h> #include <linux/wordpart.h> #include <linux/sched/cputime.h> #include <asm/div64.h> @@ -260,6 +261,16 @@ static int vmware_log_rpc(const char *buffer, size_t length) static struct page *vmware_panic_page; static bool vmware_record_panic_msg; +static const struct ctl_table vmware_panic_sysctls[] = { + { + .procname = "vmware_record_panic_msg", + .data = &vmware_record_panic_msg, + .maxlen = sizeof(vmware_record_panic_msg), + .mode = 0644, + .proc_handler = proc_dobool, + }, +}; + static int vmware_panic_log_notify(struct notifier_block *nb, unsigned long action, void *data) { @@ -311,6 +322,10 @@ static int __init vmware_panic_log_init(void) vmware_panic_page = NULL; } + if (vmware_panic_page && IS_ENABLED(CONFIG_SYSCTL) && + !register_sysctl("kernel", vmware_panic_sysctls)) + pr_err("failed to register panic log sysctl\n"); + return 0; } early_initcall(vmware_panic_log_init);
