[PATCH v4 1/4] x86/mm: Restructure sme_encrypt_kernel()

[Brijesh Singh]

Re-arrange the sme_encrypt_kernel() by moving the workarea map/unmap
logic in a separate static function. There are no logical changes in this
patch. The restructuring will allow us to expand the sme_encrypt_kernel
in future.

Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
Reviewed-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
Cc: Tom Lendacky <thomas.lendacky@xxxxxxx>
Cc: kvm@xxxxxxxxxxxxxxx
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Cc: kvm@xxxxxxxxxxxxxxx
Cc: "Radim KrÄmÃÅ" <rkrcmar@xxxxxxxxxx>
---
 arch/x86/mm/mem_encrypt_identity.c | 160 ++++++++++++++++++++++++-------------
 1 file changed, 104 insertions(+), 56 deletions(-)

diff --git a/arch/x86/mm/mem_encrypt_identity.c b/arch/x86/mm/mem_encrypt_identity.c
index 7ae3686..92265d3 100644
--- a/arch/x86/mm/mem_encrypt_identity.c
+++ b/arch/x86/mm/mem_encrypt_identity.c
@@ -72,6 +72,22 @@ struct sme_populate_pgd_data {
 	unsigned long vaddr_end;
 };
 
+struct sme_workarea_data {
+	unsigned long kernel_start;
+	unsigned long kernel_end;
+	unsigned long kernel_len;
+
+	unsigned long initrd_start;
+	unsigned long initrd_end;
+	unsigned long initrd_len;
+
+	unsigned long workarea_start;
+	unsigned long workarea_end;
+	unsigned long workarea_len;
+
+	unsigned long decrypted_base;
+};
+
 static char sme_cmdline_arg[] __initdata = "mem_encrypt";
 static char sme_cmdline_on[]  __initdata = "on";
 static char sme_cmdline_off[] __initdata = "off";
@@ -266,19 +282,17 @@ static unsigned long __init sme_pgtable_calc(unsigned long len)
 	return entries + tables;
 }
 
-void __init sme_encrypt_kernel(struct boot_params *bp)
+static void __init build_workarea_map(struct boot_params *bp,
+				      struct sme_workarea_data *wa,
+				      struct sme_populate_pgd_data *ppd)
 {
 	unsigned long workarea_start, workarea_end, workarea_len;
 	unsigned long execute_start, execute_end, execute_len;
 	unsigned long kernel_start, kernel_end, kernel_len;
 	unsigned long initrd_start, initrd_end, initrd_len;
-	struct sme_populate_pgd_data ppd;
 	unsigned long pgtable_area_len;
 	unsigned long decrypted_base;
 
-	if (!sme_active())
-		return;
-
 	/*
 	 * Prepare for encrypting the kernel and initrd by building new
 	 * pagetables with the necessary attributes needed to encrypt the
@@ -358,17 +372,17 @@ void __init sme_encrypt_kernel(struct boot_params *bp)
 	 * pagetables and when the new encrypted and decrypted kernel
 	 * mappings are populated.
 	 */
-	ppd.pgtable_area = (void *)execute_end;
+	ppd->pgtable_area = (void *)execute_end;
 
 	/*
 	 * Make sure the current pagetable structure has entries for
 	 * addressing the workarea.
 	 */
-	ppd.pgd = (pgd_t *)native_read_cr3_pa();
-	ppd.paddr = workarea_start;
-	ppd.vaddr = workarea_start;
-	ppd.vaddr_end = workarea_end;
-	sme_map_range_decrypted(&ppd);
+	ppd->pgd = (pgd_t *)native_read_cr3_pa();
+	ppd->paddr = workarea_start;
+	ppd->vaddr = workarea_start;
+	ppd->vaddr_end = workarea_end;
+	sme_map_range_decrypted(ppd);
 
 	/* Flush the TLB - no globals so cr3 is enough */
 	native_write_cr3(__native_read_cr3());
@@ -379,9 +393,9 @@ void __init sme_encrypt_kernel(struct boot_params *bp)
 	 * then be populated with new PUDs and PMDs as the encrypted and
 	 * decrypted kernel mappings are created.
 	 */
-	ppd.pgd = ppd.pgtable_area;
-	memset(ppd.pgd, 0, sizeof(pgd_t) * PTRS_PER_PGD);
-	ppd.pgtable_area += sizeof(pgd_t) * PTRS_PER_PGD;
+	ppd->pgd = ppd->pgtable_area;
+	memset(ppd->pgd, 0, sizeof(pgd_t) * PTRS_PER_PGD);
+	ppd->pgtable_area += sizeof(pgd_t) * PTRS_PER_PGD;
 
 	/*
 	 * A different PGD index/entry must be used to get different
@@ -399,75 +413,109 @@ void __init sme_encrypt_kernel(struct boot_params *bp)
 	decrypted_base <<= PGDIR_SHIFT;
 
 	/* Add encrypted kernel (identity) mappings */
-	ppd.paddr = kernel_start;
-	ppd.vaddr = kernel_start;
-	ppd.vaddr_end = kernel_end;
-	sme_map_range_encrypted(&ppd);
+	ppd->paddr = kernel_start;
+	ppd->vaddr = kernel_start;
+	ppd->vaddr_end = kernel_end;
+	sme_map_range_encrypted(ppd);
 
 	/* Add decrypted, write-protected kernel (non-identity) mappings */
-	ppd.paddr = kernel_start;
-	ppd.vaddr = kernel_start + decrypted_base;
-	ppd.vaddr_end = kernel_end + decrypted_base;
-	sme_map_range_decrypted_wp(&ppd);
+	ppd->paddr = kernel_start;
+	ppd->vaddr = kernel_start + decrypted_base;
+	ppd->vaddr_end = kernel_end + decrypted_base;
+	sme_map_range_decrypted_wp(ppd);
 
 	if (initrd_len) {
 		/* Add encrypted initrd (identity) mappings */
-		ppd.paddr = initrd_start;
-		ppd.vaddr = initrd_start;
-		ppd.vaddr_end = initrd_end;
-		sme_map_range_encrypted(&ppd);
+		ppd->paddr = initrd_start;
+		ppd->vaddr = initrd_start;
+		ppd->vaddr_end = initrd_end;
+		sme_map_range_encrypted(ppd);
 		/*
 		 * Add decrypted, write-protected initrd (non-identity) mappings
 		 */
-		ppd.paddr = initrd_start;
-		ppd.vaddr = initrd_start + decrypted_base;
-		ppd.vaddr_end = initrd_end + decrypted_base;
-		sme_map_range_decrypted_wp(&ppd);
+		ppd->paddr = initrd_start;
+		ppd->vaddr = initrd_start + decrypted_base;
+		ppd->vaddr_end = initrd_end + decrypted_base;
+		sme_map_range_decrypted_wp(ppd);
 	}
 
 	/* Add decrypted workarea mappings to both kernel mappings */
-	ppd.paddr = workarea_start;
-	ppd.vaddr = workarea_start;
-	ppd.vaddr_end = workarea_end;
-	sme_map_range_decrypted(&ppd);
+	ppd->paddr = workarea_start;
+	ppd->vaddr = workarea_start;
+	ppd->vaddr_end = workarea_end;
+	sme_map_range_decrypted(ppd);
 
-	ppd.paddr = workarea_start;
-	ppd.vaddr = workarea_start + decrypted_base;
-	ppd.vaddr_end = workarea_end + decrypted_base;
-	sme_map_range_decrypted(&ppd);
+	ppd->paddr = workarea_start;
+	ppd->vaddr = workarea_start + decrypted_base;
+	ppd->vaddr_end = workarea_end + decrypted_base;
+	sme_map_range_decrypted(ppd);
 
-	/* Perform the encryption */
-	sme_encrypt_execute(kernel_start, kernel_start + decrypted_base,
-			    kernel_len, workarea_start, (unsigned long)ppd.pgd);
+	wa->kernel_start = kernel_start;
+	wa->kernel_end = kernel_end;
+	wa->kernel_len = kernel_len;
 
-	if (initrd_len)
-		sme_encrypt_execute(initrd_start, initrd_start + decrypted_base,
-				    initrd_len, workarea_start,
-				    (unsigned long)ppd.pgd);
+	wa->initrd_start = initrd_start;
+	wa->initrd_end = initrd_end;
+	wa->initrd_len = initrd_len;
+
+	wa->workarea_start = workarea_start;
+	wa->workarea_end = workarea_end;
+	wa->workarea_len = workarea_len;
+
+	wa->decrypted_base = decrypted_base;
+}
 
+static void __init teardown_workarea_map(struct sme_workarea_data *wa,
+				         struct sme_populate_pgd_data *ppd)
+{
 	/*
 	 * At this point we are running encrypted.  Remove the mappings for
 	 * the decrypted areas - all that is needed for this is to remove
 	 * the PGD entry/entries.
 	 */
-	ppd.vaddr = kernel_start + decrypted_base;
-	ppd.vaddr_end = kernel_end + decrypted_base;
-	sme_clear_pgd(&ppd);
-
-	if (initrd_len) {
-		ppd.vaddr = initrd_start + decrypted_base;
-		ppd.vaddr_end = initrd_end + decrypted_base;
-		sme_clear_pgd(&ppd);
+	ppd->vaddr = wa->kernel_start + wa->decrypted_base;
+	ppd->vaddr_end = wa->kernel_end + wa->decrypted_base;
+	sme_clear_pgd(ppd);
+
+	if (wa->initrd_len) {
+		ppd->vaddr = wa->initrd_start + wa->decrypted_base;
+		ppd->vaddr_end = wa->initrd_end + wa->decrypted_base;
+		sme_clear_pgd(ppd);
 	}
 
-	ppd.vaddr = workarea_start + decrypted_base;
-	ppd.vaddr_end = workarea_end + decrypted_base;
-	sme_clear_pgd(&ppd);
+	ppd->vaddr = wa->workarea_start + wa->decrypted_base;
+	ppd->vaddr_end = wa->workarea_end + wa->decrypted_base;
+	sme_clear_pgd(ppd);
 
 	/* Flush the TLB - no globals so cr3 is enough */
 	native_write_cr3(__native_read_cr3());
 }
 
+void __init sme_encrypt_kernel(struct boot_params *bp)
+{
+	struct sme_populate_pgd_data ppd;
+	struct sme_workarea_data wa;
+
+	if (!sme_active())
+		return;
+
+	build_workarea_map(bp, &wa, &ppd);
+
+	/* When SEV is active, encrypt kernel and initrd */
+	sme_encrypt_execute(wa.kernel_start,
+			    wa.kernel_start + wa.decrypted_base,
+			    wa.kernel_len, wa.workarea_start,
+			    (unsigned long)ppd.pgd);
+
+	if (wa.initrd_len)
+		sme_encrypt_execute(wa.initrd_start,
+				    wa.initrd_start + wa.decrypted_base,
+				    wa.initrd_len, wa.workarea_start,
+				    (unsigned long)ppd.pgd);
+
+	teardown_workarea_map(&wa, &ppd);
+}
+
 void __init sme_enable(struct boot_params *bp)
 {
 	const char *cmdline_ptr, *cmdline_arg, *cmdline_on, *cmdline_off;
-- 
2.7.4