Re: [PATCH v2 06/12] x86/sev: Cache AP Jump Table Address

[Borislav Petkov]

On Mon, Sep 13, 2021 at 05:55:57PM +0200, Joerg Roedel wrote:
> From: Joerg Roedel 
> 
> Store the physical address of the AP Jump Table in kernel memory so
> that it does not need to be fetched from the Hypervisor again.
> 
> Signed-off-by: Joerg Roedel 
> ---
>  arch/x86/kernel/sev.c | 26 ++
>  1 file changed, 14 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
> index 5d3422e8b25e..eedba56b6bac 100644
> --- a/arch/x86/kernel/sev.c
> +++ b/arch/x86/kernel/sev.c
> @@ -42,6 +42,9 @@ static struct ghcb boot_ghcb_page __bss_decrypted 
> __aligned(PAGE_SIZE);
>   */
>  static struct ghcb __initdata *boot_ghcb;
>  
> +/* Cached AP Jump Table Address */
> +static phys_addr_t sev_es_jump_table_pa;

This is static, so "jump_table_pa" should be enough.

Also, to the prefixes, everything which is not SEV-ES only, should be
simply prefixed with "sev_" if externally visible.

Thx.

-- 
Regards/Gruss,
Boris.

https://people.kernel.org/tglx/notes-about-netiquette
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[PATCH v2 06/12] x86/sev: Cache AP Jump Table Address

[Joerg Roedel]

From: Joerg Roedel 

Store the physical address of the AP Jump Table in kernel memory so
that it does not need to be fetched from the Hypervisor again.

Signed-off-by: Joerg Roedel 
---
 arch/x86/kernel/sev.c | 26 ++
 1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 5d3422e8b25e..eedba56b6bac 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -42,6 +42,9 @@ static struct ghcb boot_ghcb_page __bss_decrypted 
__aligned(PAGE_SIZE);
  */
 static struct ghcb __initdata *boot_ghcb;
 
+/* Cached AP Jump Table Address */
+static phys_addr_t sev_es_jump_table_pa;
+
 /* #VC handler runtime per-CPU data */
 struct sev_es_runtime_data {
struct ghcb ghcb_page;
@@ -546,12 +549,14 @@ void noinstr __sev_es_nmi_complete(void)
__sev_put_ghcb();
 }
 
-static u64 get_jump_table_addr(void)
+static phys_addr_t get_jump_table_addr(void)
 {
struct ghcb_state state;
unsigned long flags;
struct ghcb *ghcb;
-   u64 ret = 0;
+
+   if (sev_es_jump_table_pa)
+   return sev_es_jump_table_pa;
 
local_irq_save(flags);
 
@@ -567,39 +572,36 @@ static u64 get_jump_table_addr(void)
 
if (ghcb_sw_exit_info_1_is_valid(ghcb) &&
ghcb_sw_exit_info_2_is_valid(ghcb))
-   ret = ghcb->save.sw_exit_info_2;
+   sev_es_jump_table_pa = (phys_addr_t)ghcb->save.sw_exit_info_2;
 
__sev_put_ghcb();
 
local_irq_restore(flags);
 
-   return ret;
+   return sev_es_jump_table_pa;
 }
 
 int sev_es_setup_ap_jump_table(struct real_mode_header *rmh)
 {
u16 startup_cs, startup_ip;
-   phys_addr_t jump_table_pa;
-   u64 jump_table_addr;
u16 __iomem *jump_table;
+   phys_addr_t pa;
 
-   jump_table_addr = get_jump_table_addr();
+   pa = get_jump_table_addr();
 
/* On UP guests there is no jump table so this is not a failure */
-   if (!jump_table_addr)
+   if (!pa)
return 0;
 
/* Check if AP Jump Table is page-aligned */
-   if (jump_table_addr & ~PAGE_MASK)
+   if (pa & ~PAGE_MASK)
return -EINVAL;
 
-   jump_table_pa = jump_table_addr & PAGE_MASK;
-
startup_cs = (u16)(rmh->trampoline_start >> 4);
startup_ip = (u16)(rmh->sev_es_trampoline_start -
   rmh->trampoline_start);
 
-   jump_table = ioremap_encrypted(jump_table_pa, PAGE_SIZE);
+   jump_table = ioremap_encrypted(pa, PAGE_SIZE);
if (!jump_table)
return -EIO;
 
-- 
2.33.0

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