linux-kernel - [tip: x86/urgent] x86/tdx: Support vmalloc() for tdx_enc_status

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Date: Tue, 25 Jun 2024 22:12:19 -0000
From: "tip-bot2 for Dexuan Cui" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
 Dexuan Cui <decui@...rosoft.com>, Dave Hansen <dave.hansen@...ux.intel.com>,
 Michael Kelley <mikelley@...rosoft.com>,
 Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>,
 Rick Edgecombe <rick.p.edgecombe@...el.com>, Kai Huang <kai.huang@...el.com>,
 stable@...r.kernel.org, x86@...nel.org, linux-kernel@...r.kernel.org
Subject:
 [tip: x86/urgent] x86/tdx: Support vmalloc() for tdx_enc_status_changed()

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     e1b8ac3aae589bb57a2c2e49fa76235c687c4d23
Gitweb:        https://git.kernel.org/tip/e1b8ac3aae589bb57a2c2e49fa76235c687c4d23
Author:        Dexuan Cui <decui@...rosoft.com>
AuthorDate:    Mon, 20 May 2024 19:12:38 -07:00
Committer:     Dave Hansen <dave.hansen@...ux.intel.com>
CommitterDate: Tue, 25 Jun 2024 14:45:22 -07:00

x86/tdx: Support vmalloc() for tdx_enc_status_changed()

When a TDX guest runs on Hyper-V, the hv_netvsc driver's netvsc_init_buf()
allocates buffers using vzalloc(), and needs to share the buffers with the
host OS by calling set_memory_decrypted(), which is not working for
vmalloc() yet. Add the support by handling the pages one by one.

Co-developed-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Signed-off-by: Dexuan Cui <decui@...rosoft.com>
Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com>
Reviewed-by: Michael Kelley <mikelley@...rosoft.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
Reviewed-by: Rick Edgecombe <rick.p.edgecombe@...el.com>
Reviewed-by: Dave Hansen <dave.hansen@...ux.intel.com>
Acked-by: Kai Huang <kai.huang@...el.com>
Cc:stable@...r.kernel.org
Link: https://lore.kernel.org/all/20240521021238.1803-1-decui%40microsoft.com
---
 arch/x86/coco/tdx/tdx.c | 35 ++++++++++++++++++++++++++++-------
 1 file changed, 28 insertions(+), 7 deletions(-)

diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c
index c1cb903..abf3cd5 100644
--- a/arch/x86/coco/tdx/tdx.c
+++ b/arch/x86/coco/tdx/tdx.c
@@ -7,6 +7,7 @@
 #include <linux/cpufeature.h>
 #include <linux/export.h>
 #include <linux/io.h>
+#include <linux/mm.h>
 #include <asm/coco.h>
 #include <asm/tdx.h>
 #include <asm/vmx.h>
@@ -778,6 +779,19 @@ static bool tdx_map_gpa(phys_addr_t start, phys_addr_t end, bool enc)
 	return false;
 }
 
+static bool tdx_enc_status_changed_phys(phys_addr_t start, phys_addr_t end,
+					bool enc)
+{
+	if (!tdx_map_gpa(start, end, enc))
+		return false;
+
+	/* shared->private conversion requires memory to be accepted before use */
+	if (enc)
+		return tdx_accept_memory(start, end);
+
+	return true;
+}
+
 /*
  * Inform the VMM of the guest's intent for this physical page: shared with
  * the VMM or private to the guest.  The VMM is expected to change its mapping
@@ -785,15 +799,22 @@ static bool tdx_map_gpa(phys_addr_t start, phys_addr_t end, bool enc)
  */
 static bool tdx_enc_status_changed(unsigned long vaddr, int numpages, bool enc)
 {
-	phys_addr_t start = __pa(vaddr);
-	phys_addr_t end   = __pa(vaddr + numpages * PAGE_SIZE);
+	unsigned long start = vaddr;
+	unsigned long end = start + numpages * PAGE_SIZE;
+	unsigned long step = end - start;
+	unsigned long addr;
 
-	if (!tdx_map_gpa(start, end, enc))
-		return false;
+	/* Step through page-by-page for vmalloc() mappings */
+	if (is_vmalloc_addr((void *)vaddr))
+		step = PAGE_SIZE;
 
-	/* shared->private conversion requires memory to be accepted before use */
-	if (enc)
-		return tdx_accept_memory(start, end);
+	for (addr = start; addr < end; addr += step) {
+		phys_addr_t start_pa = slow_virt_to_phys((void *)addr);
+		phys_addr_t end_pa   = start_pa + step;
+
+		if (!tdx_enc_status_changed_phys(start_pa, end_pa, enc))
+			return false;
+	}
 
 	return true;
 }