diff mbox series

[RFCv2,06/13] x86/realmode: Share trampoline area if KVM memory protection enabled

Message ID 20210416154106.23721-7-kirill.shutemov@linux.intel.com (mailing list archive)
State New
Headers show
Series TDX and guest memory unmapping | expand

Commit Message

Kirill A. Shutemov April 16, 2021, 3:40 p.m. UTC
If KVM memory protection is active, the trampoline area will need to be
in shared memory.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
 arch/x86/realmode/init.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

Comments

Dave Hansen April 19, 2021, 4:49 p.m. UTC | #1
On 4/16/21 8:40 AM, Kirill A. Shutemov wrote:
>  	/*
> -	 * If SME is active, the trampoline area will need to be in
> -	 * decrypted memory in order to bring up other processors
> +	 * If SME or KVM memory protection is active, the trampoline area will
> +	 * need to be in decrypted memory in order to bring up other processors
>  	 * successfully. This is not needed for SEV.
>  	 */
> -	if (sme_active())
> +	if (sme_active() || kvm_mem_protected())
>  		set_memory_decrypted((unsigned long)base, size >> PAGE_SHIFT);

Could you take a look at all the places you've added these:

	if (foo() || kvm_mem_protected())
		bar();

spots and see if some refactoring is in order?

I suspect that some thought about what the high-level commonalities are,
plus some thoughtful helper function names would go a long way to making
this whole thing understandable.


set_memory_decrypted() as a name needs to go.  It almost needs to be
something like:

	set_memory_sharing()

or something.  The "sharing" would be between the kernel and devices
(for SME), or the guest kernel and host kernel for protected memory.
diff mbox series

Patch

diff --git a/arch/x86/realmode/init.c b/arch/x86/realmode/init.c
index 22fda7d99159..f3b54b5da693 100644
--- a/arch/x86/realmode/init.c
+++ b/arch/x86/realmode/init.c
@@ -10,6 +10,7 @@ 
 #include <asm/tlbflush.h>
 #include <asm/crash.h>
 #include <asm/sev-es.h>
+#include <asm/kvm_para.h>
 
 struct real_mode_header *real_mode_header;
 u32 *trampoline_cr4_features;
@@ -75,11 +76,11 @@  static void __init setup_real_mode(void)
 	base = (unsigned char *)real_mode_header;
 
 	/*
-	 * If SME is active, the trampoline area will need to be in
-	 * decrypted memory in order to bring up other processors
+	 * If SME or KVM memory protection is active, the trampoline area will
+	 * need to be in decrypted memory in order to bring up other processors
 	 * successfully. This is not needed for SEV.
 	 */
-	if (sme_active())
+	if (sme_active() || kvm_mem_protected())
 		set_memory_decrypted((unsigned long)base, size >> PAGE_SHIFT);
 
 	memcpy(base, real_mode_blob, size);