2022-11-28 02:07:52

by Dexuan Cui

Subject: [PATCH] x86/sev: mem_encrypt_free_decrypted_mem(): encrypt the pages for AMD SME only

sme_postprocess_startup() marks the __start_bss_decrypted pages shared
for AMD SME only, so here set_memory_encrypted() should be called for AMD
SME only, i.e. don't call the set_memory_encrypted() for TDX, otherwise the
error "failed to free unused decrypted pages" appears in 'dmesg'.

Fixes: b3f0907c71e0 ("x86/mm: Add .bss..decrypted section to hold shared variables")
Signed-off-by: Dexuan Cui <[email protected]>
---
arch/x86/mm/mem_encrypt_amd.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/mm/mem_encrypt_amd.c b/arch/x86/mm/mem_encrypt_amd.c
index 9c4d8dbcb129..fd9b58402a22 100644
--- a/arch/x86/mm/mem_encrypt_amd.c
+++ b/arch/x86/mm/mem_encrypt_amd.c
@@ -516,7 +516,7 @@ void __init mem_encrypt_free_decrypted_mem(void)
* The unused memory range was mapped decrypted, change the encryption
* attribute from decrypted to encrypted before freeing it.
*/
- if (cc_platform_has(CC_ATTR_MEM_ENCRYPT)) {
+ if (sme_me_mask && cc_platform_has(CC_ATTR_MEM_ENCRYPT)) {
r = set_memory_encrypted(vaddr, npages);
if (r) {
pr_warn("failed to free unused decrypted pages\n");
--
2.25.1

2022-11-28 02:46:52

by Dexuan Cui

Subject: RE: [PATCH] x86/sev: mem_encrypt_free_decrypted_mem(): encrypt the pages for AMD SME only

> From: Dexuan Cui <[email protected]>
> Sent: Sunday, November 27, 2022 5:29 PM
> To: [email protected]; [email protected]; [email protected];
> [email protected]; [email protected]; [email protected]; [email protected];
> [email protected]; [email protected]
> Cc: [email protected]; [email protected]; Dexuan Cui
> <[email protected]>
> Subject: [PATCH] x86/sev: mem_encrypt_free_decrypted_mem(): encrypt the
> pages for AMD SME only
>
> sme_postprocess_startup() marks the __start_bss_decrypted pages shared
> for AMD SME only, so here set_memory_encrypted() should be called for AMD
> SME only, i.e. don't call the set_memory_encrypted() for TDX, otherwise the
> error "failed to free unused decrypted pages" appears in 'dmesg'.
>
> Fixes: b3f0907c71e0 ("x86/mm: Add .bss..decrypted section to hold shared
> variables")
> Signed-off-by: Dexuan Cui <[email protected]>
> ---
> arch/x86/mm/mem_encrypt_amd.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/mm/mem_encrypt_amd.c
> b/arch/x86/mm/mem_encrypt_amd.c
> index 9c4d8dbcb129..fd9b58402a22 100644
> --- a/arch/x86/mm/mem_encrypt_amd.c
> +++ b/arch/x86/mm/mem_encrypt_amd.c
> @@ -516,7 +516,7 @@ void __init mem_encrypt_free_decrypted_mem(void)
> * The unused memory range was mapped decrypted, change the
> encryption
> * attribute from decrypted to encrypted before freeing it.
> */
> - if (cc_platform_has(CC_ATTR_MEM_ENCRYPT)) {
> + if (sme_me_mask && cc_platform_has(CC_ATTR_MEM_ENCRYPT)) {
> r = set_memory_encrypted(vaddr, npages);
> if (r) {
> pr_warn("failed to free unused decrypted pages\n");
> --

Please ignore this patch as Michael posted a similar patch earlier:
https://lwn.net/ml/linux-kernel/1668624097-14884-6-git-send-email-mikelley%40microsoft.com/