[PATCH v2 6/6] x86/boot: Use copied boot data in sme_enable()

Brian Gerst
2023-04-12T18:45:39Z

Use the copied version instead of the original real mode data.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
---
arch/x86/include/asm/mem_encrypt.h | 4 +--
arch/x86/kernel/head_64.S | 8 +-----
arch/x86/mm/mem_encrypt_identity.c | 42 ++++++++++++++++--------------
3 files changed, 26 insertions(+), 28 deletions(-)

diff --git a/arch/x86/include/asm/mem_encrypt.h b/arch/x86/include/asm/mem_encrypt.h
index b7126701574c..74f094eb88a6 100644
--- a/arch/x86/include/asm/mem_encrypt.h
+++ b/arch/x86/include/asm/mem_encrypt.h
@@ -40,7 +40,7 @@ void __init sme_early_init(void);
void __init sev_setup_arch(void);

void __init sme_encrypt_kernel(struct boot_params *bp);
-void __init sme_enable(struct boot_params *bp);
+void __init sme_enable(void);

int __init early_set_memory_decrypted(unsigned long vaddr, unsigned long size);
int __init early_set_memory_encrypted(unsigned long vaddr, unsigned long size);
@@ -70,7 +70,7 @@ static inline void __init sme_early_init(void) { }
static inline void __init sev_setup_arch(void) { }

static inline void __init sme_encrypt_kernel(struct boot_params *bp) { }
-static inline void __init sme_enable(struct boot_params *bp) { }
+static inline void __init sme_enable(void) { }

static inline void sev_es_init_vc_handling(void) { }

diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index c7b2ef379f42..c6ea37712921 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -72,14 +72,11 @@ SYM_CODE_START_NOALIGN(startup_64)
wrmsr

leaq _text(%rip), %rdi
- pushq %rsi
+ /* RSI contains address of real_mode_data */
call copy_bootdata
- popq %rsi

leaq _text(%rip), %rdi
- pushq %rsi
call startup_64_setup_env
- popq %rsi

#ifdef CONFIG_AMD_MEM_ENCRYPT
/*
@@ -88,10 +85,7 @@ SYM_CODE_START_NOALIGN(startup_64)
* which needs to be done before any CPUID instructions are executed in
* subsequent code.
*/
- movq %rsi, %rdi
- pushq %rsi
call sme_enable
- popq %rsi
#endif

/* Now switch to __KERNEL_CS so IRET works reliably */
diff --git a/arch/x86/mm/mem_encrypt_identity.c b/arch/x86/mm/mem_encrypt_identity.c
index c6efcf559d88..e75e4f5a8a71 100644
--- a/arch/x86/mm/mem_encrypt_identity.c
+++ b/arch/x86/mm/mem_encrypt_identity.c
@@ -502,8 +502,9 @@ void __init sme_encrypt_kernel(struct boot_params *bp)
native_write_cr3(__native_read_cr3());
}

-void __init sme_enable(struct boot_params *bp)
+void __init sme_enable(void)
{
+ struct boot_params *bp;
const char *cmdline_ptr, *cmdline_arg, *cmdline_on, *cmdline_off;
unsigned int eax, ebx, ecx, edx;
unsigned long feature_mask;
@@ -513,6 +514,27 @@ void __init sme_enable(struct boot_params *bp)
bool snp;
u64 msr;

+ /*
+ * Fixups have not been applied to phys_base yet and we're running
+ * identity mapped, so we must obtain the address to global data
+ * using rip-relative addressing.
+ */
+ asm("lea sme_cmdline_arg(%%rip), %0"
+ : "=r" (cmdline_arg)
+ : "p" (sme_cmdline_arg));
+ asm("lea sme_cmdline_on(%%rip), %0"
+ : "=r" (cmdline_on)
+ : "p" (sme_cmdline_on));
+ asm("lea sme_cmdline_off(%%rip), %0"
+ : "=r" (cmdline_off)
+ : "p" (sme_cmdline_off));
+ asm("lea boot_params(%%rip), %0"
+ : "=r" (bp)
+ : "m" (boot_params));
+ asm("lea boot_command_line(%%rip), %0"
+ : "=r" (cmdline_ptr)
+ : "p" (boot_command_line));
+
snp = snp_init(bp);

/* Check for the SME/SEV support leaf */
@@ -577,29 +599,11 @@ void __init sme_enable(struct boot_params *bp)
goto out;
}

- /*
- * Fixups have not been applied to phys_base yet and we're running
- * identity mapped, so we must obtain the address to the SME command
- * line argument data using rip-relative addressing.
- */
- asm ("lea sme_cmdline_arg(%%rip), %0"
- : "=r" (cmdline_arg)
- : "p" (sme_cmdline_arg));
- asm ("lea sme_cmdline_on(%%rip), %0"
- : "=r" (cmdline_on)
- : "p" (sme_cmdline_on));
- asm ("lea sme_cmdline_off(%%rip), %0"
- : "=r" (cmdline_off)
- : "p" (sme_cmdline_off));
-
if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT))
active_by_default = true;
else
active_by_default = false;

- cmdline_ptr = (const char *)((u64)bp->hdr.cmd_line_ptr |
- ((u64)bp->ext_cmd_line_ptr << 32));
-
if (cmdline_find_option(cmdline_ptr, cmdline_arg, buffer, sizeof(buffer)) < 0)
return;

--
2.39.2