Merge branch 'x86-kdump-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x865 kdump updates from Thomas Gleixner:
 "Yet more kexec/kdump updates:

   - Properly support kexec when AMD's memory encryption (SME) is
     enabled

   - Pass reserved e820 ranges to the kexec kernel so both PCI and SME
     can work"

* 'x86-kdump-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  fs/proc/vmcore: Enable dumping of encrypted memory when SEV was active
  x86/kexec: Set the C-bit in the identity map page table when SEV is active
  x86/kexec: Do not map kexec area as decrypted when SEV is active
  x86/crash: Add e820 reserved ranges to kdump kernel's e820 table
  x86/mm: Rework ioremap resource mapping determination
  x86/e820, ioport: Add a new I/O resource descriptor IORES_DESC_RESERVED
  x86/mm: Create a workarea in the kernel for SME early encryption
  x86/mm: Identify the end of the kernel area to be reserved

2 files changed, 65 insertions, 28 deletions

diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 4b6423e7bd21..e500f1df1140 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -28,9 +28,11 @@
 
 #include "physaddr.h"
 
-struct ioremap_mem_flags {
-	bool system_ram;
-	bool desc_other;
+/*
+ * Descriptor controlling ioremap() behavior.
+ */
+struct ioremap_desc {
+	unsigned int flags;
 };
 
 /*
@@ -62,13 +64,14 @@ int ioremap_change_attr(unsigned long vaddr, unsigned long size,
 	return err;
 }
 
-static bool __ioremap_check_ram(struct resource *res)
+/* Does the range (or a subset of) contain normal RAM? */
+static unsigned int __ioremap_check_ram(struct resource *res)
 {
 	unsigned long start_pfn, stop_pfn;
 	unsigned long i;
 
 	if ((res->flags & IORESOURCE_SYSTEM_RAM) != IORESOURCE_SYSTEM_RAM)
-		return false;
+		return 0;
 
 	start_pfn = (res->start + PAGE_SIZE - 1) >> PAGE_SHIFT;
 	stop_pfn = (res->end + 1) >> PAGE_SHIFT;
@@ -76,28 +79,44 @@ static bool __ioremap_check_ram(struct resource *res)
 		for (i = 0; i < (stop_pfn - start_pfn); ++i)
 			if (pfn_valid(start_pfn + i) &&
 			    !PageReserved(pfn_to_page(start_pfn + i)))
-				return true;
+				return IORES_MAP_SYSTEM_RAM;
 	}
 
-	return false;
+	return 0;
 }
 
-static int __ioremap_check_desc_other(struct resource *res)
+/*
+ * In a SEV guest, NONE and RESERVED should not be mapped encrypted because
+ * there the whole memory is already encrypted.
+ */
+static unsigned int __ioremap_check_encrypted(struct resource *res)
 {
-	return (res->desc != IORES_DESC_NONE);
+	if (!sev_active())
+		return 0;
+
+	switch (res->desc) {
+	case IORES_DESC_NONE:
+	case IORES_DESC_RESERVED:
+		break;
+	default:
+		return IORES_MAP_ENCRYPTED;
+	}
+
+	return 0;
 }
 
-static int __ioremap_res_check(struct resource *res, void *arg)
+static int __ioremap_collect_map_flags(struct resource *res, void *arg)
 {
-	struct ioremap_mem_flags *flags = arg;
+	struct ioremap_desc *desc = arg;
 
-	if (!flags->system_ram)
-		flags->system_ram = __ioremap_check_ram(res);
+	if (!(desc->flags & IORES_MAP_SYSTEM_RAM))
+		desc->flags |= __ioremap_check_ram(res);
 
-	if (!flags->desc_other)
-		flags->desc_other = __ioremap_check_desc_other(res);
+	if (!(desc->flags & IORES_MAP_ENCRYPTED))
+		desc->flags |= __ioremap_check_encrypted(res);
 
-	return flags->system_ram && flags->desc_other;
+	return ((desc->flags & (IORES_MAP_SYSTEM_RAM | IORES_MAP_ENCRYPTED)) ==
+			       (IORES_MAP_SYSTEM_RAM | IORES_MAP_ENCRYPTED));
 }
 
 /*
@@ -106,15 +125,15 @@ static int __ioremap_res_check(struct resource *res, void *arg)
  * resource described not as IORES_DESC_NONE (e.g. IORES_DESC_ACPI_TABLES).
  */
 static void __ioremap_check_mem(resource_size_t addr, unsigned long size,
-				struct ioremap_mem_flags *flags)
+				struct ioremap_desc *desc)
 {
 	u64 start, end;
 
 	start = (u64)addr;
 	end = start + size - 1;
-	memset(flags, 0, sizeof(*flags));
+	memset(desc, 0, sizeof(struct ioremap_desc));
 
-	walk_mem_res(start, end, flags, __ioremap_res_check);
+	walk_mem_res(start, end, desc, __ioremap_collect_map_flags);
 }
 
 /*
@@ -131,15 +150,15 @@ static void __ioremap_check_mem(resource_size_t addr, unsigned long size,
  * have to convert them into an offset in a page-aligned mapping, but the
  * caller shouldn't need to know that small detail.
  */
-static void __iomem *__ioremap_caller(resource_size_t phys_addr,
-		unsigned long size, enum page_cache_mode pcm,
-		void *caller, bool encrypted)
+static void __iomem *
+__ioremap_caller(resource_size_t phys_addr, unsigned long size,
+		 enum page_cache_mode pcm, void *caller, bool encrypted)
 {
 	unsigned long offset, vaddr;
 	resource_size_t last_addr;
 	const resource_size_t unaligned_phys_addr = phys_addr;
 	const unsigned long unaligned_size = size;
-	struct ioremap_mem_flags mem_flags;
+	struct ioremap_desc io_desc;
 	struct vm_struct *area;
 	enum page_cache_mode new_pcm;
 	pgprot_t prot;
@@ -158,12 +177,12 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr,
 		return NULL;
 	}
 
-	__ioremap_check_mem(phys_addr, size, &mem_flags);
+	__ioremap_check_mem(phys_addr, size, &io_desc);
 
 	/*
 	 * Don't allow anybody to remap normal RAM that we're using..
 	 */
-	if (mem_flags.system_ram) {
+	if (io_desc.flags & IORES_MAP_SYSTEM_RAM) {
 		WARN_ONCE(1, "ioremap on RAM at %pa - %pa\n",
 			  &phys_addr, &last_addr);
 		return NULL;
@@ -201,7 +220,7 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr,
 	 * resulting mapping.
 	 */
 	prot = PAGE_KERNEL_IO;
-	if ((sev_active() && mem_flags.desc_other) || encrypted)
+	if ((io_desc.flags & IORES_MAP_ENCRYPTED) || encrypted)
 		prot = pgprot_encrypted(prot);
 
 	switch (pcm) {
diff --git a/arch/x86/mm/mem_encrypt_identity.c b/arch/x86/mm/mem_encrypt_identity.c
index dddcd2a1afdb..e2b0e2ac07bb 100644
--- a/arch/x86/mm/mem_encrypt_identity.c
+++ b/arch/x86/mm/mem_encrypt_identity.c
@@ -70,6 +70,19 @@ struct sme_populate_pgd_data {
 	unsigned long vaddr_end;
 };
 
+/*
+ * This work area lives in the .init.scratch section, which lives outside of
+ * the kernel proper. It is sized to hold the intermediate copy buffer and
+ * more than enough pagetable pages.
+ *
+ * By using this section, the kernel can be encrypted in place and it
+ * avoids any possibility of boot parameters or initramfs images being
+ * placed such that the in-place encryption logic overwrites them.  This
+ * section is 2MB aligned to allow for simple pagetable setup using only
+ * PMD entries (see vmlinux.lds.S).
+ */
+static char sme_workarea[2 * PMD_PAGE_SIZE] __section(.init.scratch);
+
 static char sme_cmdline_arg[] __initdata = "mem_encrypt";
 static char sme_cmdline_on[]  __initdata = "on";
 static char sme_cmdline_off[] __initdata = "off";
@@ -311,8 +324,13 @@ void __init sme_encrypt_kernel(struct boot_params *bp)
 	}
 #endif
 
-	/* Set the encryption workarea to be immediately after the kernel */
-	workarea_start = kernel_end;
+	/*
+	 * We're running identity mapped, so we must obtain the address to the
+	 * SME encryption workarea using rip-relative addressing.
+	 */
+	asm ("lea sme_workarea(%%rip), %0"
+	     : "=r" (workarea_start)
+	     : "p" (sme_workarea));
 
 	/*
 	 * Calculate required number of workarea bytes needed: