[PATCH V7 2/5] x86/hyper-v: Add hyperv Isolation VM check in the cc_platform_has()

[Tianyu Lan <ltykernel@gmail.com>]

From: Tianyu Lan <Tianyu.Lan@microsoft.com>

Hyper-V provides Isolation VM for confidential computing support and
guest memory is encrypted in it. Places checking cc_platform_has()
with GUEST_MEM_ENCRYPT attr should return "True" in Isolation vm. e.g,
swiotlb bounce buffer size needs to adjust according to memory size
in the sev_setup_arch(). Add GUEST_MEM_ENCRYPT check for Hyper-V Isolation
VM.

Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
---
Change since v6:
	* Change the order in the cc_platform_has() and check sev first.

Change since v3:
	* Change code style of checking GUEST_MEM attribute in the
	  hyperv_cc_platform_has().
---
 arch/x86/kernel/cc_platform.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/x86/kernel/cc_platform.c b/arch/x86/kernel/cc_platform.c
index 03bb2f343ddb..6cb3a675e686 100644
--- a/arch/x86/kernel/cc_platform.c
+++ b/arch/x86/kernel/cc_platform.c
@@ -11,6 +11,7 @@
 #include <linux/cc_platform.h>
 #include <linux/mem_encrypt.h>
 
+#include <asm/mshyperv.h>
 #include <asm/processor.h>
 
 static bool __maybe_unused intel_cc_platform_has(enum cc_attr attr)
@@ -58,12 +59,19 @@ static bool amd_cc_platform_has(enum cc_attr attr)
 #endif
 }
 
+static bool hyperv_cc_platform_has(enum cc_attr attr)
+{
+	return attr == CC_ATTR_GUEST_MEM_ENCRYPT;
+}
 
 bool cc_platform_has(enum cc_attr attr)
 {
 	if (sme_me_mask)
 		return amd_cc_platform_has(attr);
 
+	if (hv_is_isolation_supported())
+		return hyperv_cc_platform_has(attr);
+
 	return false;
 }
 EXPORT_SYMBOL_GPL(cc_platform_has);
-- 
2.25.1