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Subject[PATCH v4 1/4] x86/mm: Restructure sme_encrypt_kernel()
Date
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@amd.com>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: kvm@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: linux-kernel@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: kvm@vger.kernel.org
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
---
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
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