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Subject[RFC PATCH 06/12] x86/sev: Cache AP Jump Table Address
Date
From: Joerg Roedel <jroedel@suse.de>

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 <jroedel@suse.de>
---
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(&state);
}

-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(&state);

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;

--
2.31.1
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