[PATCH v2 09/17] x86/virt/tdx: Add interface to check Quoting availability

[Xu Yilun <yilun.xu@linux.intel.com>]

From: Peter Fang <peter.fang@intel.com>

KVM needs to know if the Quoting extension is available to determine
whether userspace must be involved in Quote generation.

Since the Quote buffer is always created during Quoting extension
bringup, checking whether the buffer exists is sufficient.

Signed-off-by: Peter Fang <peter.fang@intel.com>
Signed-off-by: Xu Yilun <yilun.xu@linux.intel.com>
---
 arch/x86/include/asm/tdx.h  |  2 ++
 arch/x86/virt/vmx/tdx/tdx.c | 10 ++++++++++
 2 files changed, 12 insertions(+)

diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
index 741fd97cc199..9432a736855e 100644
--- a/arch/x86/include/asm/tdx.h
+++ b/arch/x86/include/asm/tdx.h
@@ -147,6 +147,8 @@ struct tdx_vp {
 	struct page **tdcx_pages;
 };
 
+bool tdx_quote_enabled(void);
+
 static inline u64 mk_keyed_paddr(u16 hkid, struct page *page)
 {
 	u64 ret;
diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index 9716424a301f..da55c1aeeeb8 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -1193,6 +1193,16 @@ static inline phys_addr_t tdx_vmalloc_to_pa(const void *addr)
 	return PFN_PHYS(pfn);
 }
 
+bool tdx_quote_enabled(void)
+{
+	/*
+	 * No need for locking here. The quote buffer is initialized as part of
+	 * core TDX bringup, which comes before KVM is ready for userspace.
+	 */
+	return !!tdx_quote.buf;
+}
+EXPORT_SYMBOL_FOR_KVM(tdx_quote_enabled);
+
 #define HPAS_PER_NODE			(PAGE_SIZE / sizeof(u64))
 
 /*
-- 
2.25.1