Re: [kvm-unit-tests PATCH v3 2/4] x86/efi: Retry call to efi exit boot services

[Andrew Jones <andrew.jones@linux.dev>]

On Thu, Mar 28, 2024 at 10:21:10AM -0500, Pavan Kumar Paluri wrote:
> In some cases, KUT guest might fail to exit boot services due to a
> possible memory map update that might have taken place between
> efi_get_memory_map() and efi_exit_boot_services() calls. As per UEFI
> spec 2.10 (Section 7.4.6 EFI_BOOT_SERVICES.ExitBootServices()), we need
> to keep trying to update the memory map and calls to exit boot
> services as long as case status is EFI_INVALID_PARAMETER. Keep freeing
> the old memory map before obtaining new memory map via
> efi_get_memory_map() in case of exit boot services failure.
> 
> Signed-off-by: Pavan Kumar Paluri <papaluri@amd.com>
> ---
>  lib/efi.c | 34 ++++++++++++++++++++--------------
>  1 file changed, 20 insertions(+), 14 deletions(-)
> 
> diff --git a/lib/efi.c b/lib/efi.c
> index 8a74a22834a4..d2569b22b4f2 100644
> --- a/lib/efi.c
> +++ b/lib/efi.c
> @@ -406,8 +406,8 @@ efi_status_t efi_main(efi_handle_t handle, efi_system_table_t *sys_tab)
>  	efi_system_table = sys_tab;
>  
>  	/* Memory map struct values */
> -	efi_memory_desc_t *map = NULL;
> -	unsigned long map_size = 0, desc_size = 0, key = 0, buff_size = 0;
> +	efi_memory_desc_t *map;
> +	unsigned long map_size, desc_size, key, buff_size;
>  	u32 desc_ver;
>  
>  	/* Helper variables needed to get the cmdline */
> @@ -446,13 +446,6 @@ efi_status_t efi_main(efi_handle_t handle, efi_system_table_t *sys_tab)
>  	efi_bootinfo.mem_map.key_ptr = &key;
>  	efi_bootinfo.mem_map.buff_size = &buff_size;
>  
> -	/* Get EFI memory map */
> -	status = efi_get_memory_map(&efi_bootinfo.mem_map);
> -	if (status != EFI_SUCCESS) {
> -		printf("Failed to get memory map\n");
> -		goto efi_main_error;
> -	}
> -
>  #ifdef __riscv
>  	status = efi_get_boot_hartid();
>  	if (status != EFI_SUCCESS) {
> @@ -461,11 +454,24 @@ efi_status_t efi_main(efi_handle_t handle, efi_system_table_t *sys_tab)
>  	}
>  #endif
>  
> -	/* 
> -	 * Exit EFI boot services, let kvm-unit-tests take full control of the
> -	 * guest
> -	 */
> -	status = efi_exit_boot_services(handle, &efi_bootinfo.mem_map);
> +	status = EFI_INVALID_PARAMETER;
> +	while (status == EFI_INVALID_PARAMETER) {
> +		/* Get EFI memory map */

I tried to get rid of this comment since it states the exact same thing
as the function name below does.

> +		status = efi_get_memory_map(&efi_bootinfo.mem_map);
> +		if (status != EFI_SUCCESS) {
> +			printf("Failed to get memory map\n");
> +			goto efi_main_error;
> +		}
> +		/*
> +		 * Exit EFI boot services, let kvm-unit-tests take full
> +		 * control of the guest.
> +		 */
> +		status = efi_exit_boot_services(handle,
> +						&efi_bootinfo.mem_map);

We have 100 char lines (and that's just a soft limit) so this would look
better sticking out.

> +		if (status == EFI_INVALID_PARAMETER)
> +			efi_free_pool(*efi_bootinfo.mem_map.map);
> +	}
> +
>  	if (status != EFI_SUCCESS) {
>  		printf("Failed to exit boot services\n");
>  		goto efi_main_error;
> -- 
> 2.34.1
>

Besides the nits,

Reviewed-by: Andrew Jones <andrew.jones@linux.dev>

(A general comment for the series is that we're on v3 but there's no
changelog anywhere. Please use cover letters for a series and then
put the changelog in the cover letter.)

Thanks,
drew