On 01/16/2017 05:07 PM, Ralf Ramsauer wrote:
> This allows us to dump messages if the hypervisor failed to start or the
> last few messages after the hypervisor was disabled. This needs some
> special treatment, as the hypervisor_memory region is unmapped after
> failures.
>
> Hook into disable an failure paths and copy the page to a dedicated
> variable. Indicate with a boolean flag that data is present.
>
> Signed-off-by: Ralf Ramsauer <[email protected]>
> ---
> driver/main.c | 40 +++++++++++++++++++++++++++++++++++++---
> 1 file changed, 37 insertions(+), 3 deletions(-)
>
> diff --git a/driver/main.c b/driver/main.c
> index f98e63c6..807514bc 100644
> --- a/driver/main.c
> +++ b/driver/main.c
> @@ -84,6 +84,16 @@ static int error_code;
> static struct jailhouse_console *console_page;
> static bool console_available;
>
> +/* dump_last_console_page will be true in two cases:
> + * - the jailhouse console page when disabling the hypervisor
> + * - the jailhouse console page when enabling the hypervisor fails
> + *
> + * In these cases, we must copy the console_page to last_console_page before
> + * the hypervisor_mem region is unmapped.
> + */
> +static bool dump_last_console_page;
> +static struct jailhouse_console last_console_page;
> +
> #ifdef CONFIG_X86
> bool jailhouse_use_vmcall;
>
> @@ -298,6 +308,9 @@ static int jailhouse_cmd_enable(struct jailhouse_system
> __user *arg)
> long max_cpus;
> int err;
>
> + /* unset the dump_last_console_page to drop pending content */
> + dump_last_console_page = false;
> +
> fw_name = jailhouse_get_fw_name();
> if (!fw_name) {
> pr_err("jailhouse: Missing or unsupported HVM technology\n");
> @@ -477,6 +490,10 @@ static int jailhouse_cmd_enable(struct jailhouse_system
> __user *arg)
> return 0;
>
> error_free_cell:
> + if (console_available) {
> + copy_console_page(&last_console_page);
> + dump_last_console_page = true;
> + }
> jailhouse_cell_delete_root();
>
> error_unmap:
> @@ -576,6 +593,11 @@ static int jailhouse_cmd_disable(void)
> if (err)
> goto unlock_out;
>
> + if (console_available) {
> + copy_console_page(&last_console_page);
> + dump_last_console_page = true;
> + }
> +
> vunmap(hypervisor_mem);
>
> jailhouse_cell_delete_root();
> @@ -660,9 +682,21 @@ static ssize_t jailhouse_console_read(struct file *file,
> char __user *out,
>
> /* wait for new data */
> while (1) {
> - ret = jailhouse_console_page_delta(content, user->head, &miss);
> - if ((!ret || ret == -EAGAIN) && file->f_flags & O_NONBLOCK)
> - goto console_free_out;
> + if (dump_last_console_page) {
> + ret = jailhouse_console_delta(&last_console_page,
> + content, user->head,
> + &miss);
> + if (ret == 0) {
> + dump_last_console_page = false;
> + goto console_free_out;
> + }
Just found a little regression here:
If there is more than one reader, only one of them will dump the
last_console_page. FCFS...
This would not be the case if we would have a threaded periodical common
consumer of the (last_)console_page.
Ralf
> + } else {
> + ret = jailhouse_console_page_delta(content, user->head,
> + &miss);
> + if ((!ret || ret == -EAGAIN) &&
> + file->f_flags & O_NONBLOCK)
> + goto console_free_out;
> + }
>
> if (ret == -EAGAIN)
> /* Reset the user head, if jailhouse is not enabled. We
>
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