linux-kernel - [RFCv1 6/7] x86/realmode: Share trampoline area if KVM memory protection enabled

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Date:   Fri,  2 Apr 2021 18:26:44 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Sean Christopherson <seanjc@...gle.com>,
        Jim Mattson <jmattson@...gle.com>
Cc:     David Rientjes <rientjes@...gle.com>,
        "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>,
        "Kleen, Andi" <andi.kleen@...el.com>,
        "Yamahata, Isaku" <isaku.yamahata@...el.com>, x86@...nel.org,
        kvm@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: [RFCv1 6/7] x86/realmode: Share trampoline area if KVM memory protection enabled

If KVM memory protection is active, the trampoline area will need to be
in shared memory.

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

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);
-- 
2.26.3