Re: [PATCH v4 1/4] kexec: avoid compat_alloc_user_space

[Arnd Bergmann]

On Tue, Jul 20, 2021 at 5:37 PM Christoph Hellwig  wrote:
>
> This can be simplified a little more by killing off
> copy_user_segment_list entirely, using memdup_user and dropping the
> not really required _locked wrapper.  The locking move might make
> most sense as a separate prep patch.

Ok, I've integrated this as separate patches into my series now, will resend
after some more build testing.

  Arnd

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Re: [PATCH 04/12] x86/sev: Do not hardcode GHCB protocol version

[Tom Lendacky]

On 7/21/21 9:20 AM, Joerg Roedel wrote:
> From: Joerg Roedel 
> 
> Introduce the sev_get_ghcb_proto_ver() which will return the negotiated
> GHCB protocol version and use it to set the version field in the GHCB.
> 
> Signed-off-by: Joerg Roedel 
> ---
>  arch/x86/boot/compressed/sev.c | 5 +
>  arch/x86/kernel/sev-shared.c   | 5 -
>  arch/x86/kernel/sev.c  | 5 +
>  3 files changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c
> index 1a2e49730f8b..101e08c67296 100644
> --- a/arch/x86/boot/compressed/sev.c
> +++ b/arch/x86/boot/compressed/sev.c
> @@ -119,6 +119,11 @@ static enum es_result vc_read_mem(struct es_em_ctxt 
> *ctxt,
>  /* Include code for early handlers */
>  #include "../../kernel/sev-shared.c"
>  
> +static u64 sev_get_ghcb_proto_ver(void)
> +{
> + return GHCB_PROTOCOL_MAX;
> +}
> +
>  static bool early_setup_sev_es(void)
>  {
>   if (!sev_es_negotiate_protocol(NULL))
> diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c
> index 73eeb5897d16..36eaac2773ed 100644
> --- a/arch/x86/kernel/sev-shared.c
> +++ b/arch/x86/kernel/sev-shared.c
> @@ -28,6 +28,9 @@ struct sev_ghcb_protocol_info {
>   unsigned int vm_proto;
>  };
>  
> +/* Returns the negotiated GHCB Protocol version */
> +static u64 sev_get_ghcb_proto_ver(void);
> +
>  static bool __init sev_es_check_cpu_features(void)
>  {
>   if (!has_cpuflag(X86_FEATURE_RDRAND)) {
> @@ -122,7 +125,7 @@ static enum es_result sev_es_ghcb_hv_call(struct ghcb 
> *ghcb,
>   enum es_result ret;
>  
>   /* Fill in protocol and format specifiers */
> - ghcb->protocol_version = GHCB_PROTOCOL_MAX;
> + ghcb->protocol_version = sev_get_ghcb_proto_ver();

So this probably needs better clarification in the spec, but the GHCB
version field is for the GHCB structure layout. So if you don't plan to
use the XSS field that was added for version 2 of the layout, then you
should report the GHCB structure version as 1.

Thanks,
Tom

>   ghcb->ghcb_usage   = GHCB_DEFAULT_USAGE;
>  
>   ghcb_set_sw_exit_code(ghcb, exit_code);
> diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
> index 8084bfd7cce1..5d3422e8b25e 100644
> --- a/arch/x86/kernel/sev.c
> +++ b/arch/x86/kernel/sev.c
> @@ -498,6 +498,11 @@ static enum es_result vc_slow_virt_to_phys(struct ghcb 
> *ghcb, struct es_em_ctxt
>  /* Negotiated GHCB protocol version */
>  static struct sev_ghcb_protocol_info ghcb_protocol_info __ro_after_init;
>  
> +static u64 sev_get_ghcb_proto_ver(void)
> +{
> + return ghcb_protocol_info.vm_proto;
> +}
> +
>  static noinstr void __sev_put_ghcb(struct ghcb_state *state)
>  {
>   struct sev_es_runtime_data *data;
> 

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Re: [PATCH printk v4 3/6] printk: remove safe buffers

[Petr Mladek]

On Thu 2021-07-15 21:39:56, John Ogness wrote:
> With @logbuf_lock removed, the high level printk functions for
> storing messages are lockless. Messages can be stored from any
> context, so there is no need for the NMI and safe buffers anymore.
> Remove the NMI and safe buffers.
> 
> Although the safe buffers are removed, the NMI and safe context
> tracking is still in place. In these contexts, store the message
> immediately but still use irq_work to defer the console printing.
> 
> Since printk recursion tracking is in place, safe context tracking
> for most of printk is not needed. Remove it. Only safe context
> tracking relating to the console and console_owner locks is left
> in place. This is because the console and console_owner locks are
> needed for the actual printing.
> 
> Signed-off-by: John Ogness 

Reviewed-by: Petr Mladek 

Best Regards,
Petr

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