linux-kernel - [PATCH 5.5 112/151] x86/ioremap: Map EFI runtime services data as encrypted for SEV

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Date:   Tue, 17 Mar 2020 11:55:22 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Tom Lendacky <thomas.lendacky@....com>,
        Borislav Petkov <bp@...e.de>, Joerg Roedel <jroedel@...e.de>
Subject: [PATCH 5.5 112/151] x86/ioremap: Map EFI runtime services data as encrypted for SEV

From: Tom Lendacky <thomas.lendacky@....com>

commit 985e537a4082b4635754a57f4f95430790afee6a upstream.

The dmidecode program fails to properly decode the SMBIOS data supplied
by OVMF/UEFI when running in an SEV guest. The SMBIOS area, under SEV, is
encrypted and resides in reserved memory that is marked as EFI runtime
services data.

As a result, when memremap() is attempted for the SMBIOS data, it
can't be mapped as regular RAM (through try_ram_remap()) and, since
the address isn't part of the iomem resources list, it isn't mapped
encrypted through the fallback ioremap().

Add a new __ioremap_check_other() to deal with memory types like
EFI_RUNTIME_SERVICES_DATA which are not covered by the resource ranges.

This allows any runtime services data which has been created encrypted,
to be mapped encrypted too.

 [ bp: Move functionality to a separate function. ]

Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Reviewed-by: Joerg Roedel <jroedel@...e.de>
Tested-by: Joerg Roedel <jroedel@...e.de>
Cc: <stable@...r.kernel.org> # 5.3
Link: https://lkml.kernel.org/r/2d9e16eb5b53dc82665c95c6764b7407719df7a0.1582645327.git.thomas.lendacky@amd.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/x86/mm/ioremap.c |   18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -106,6 +106,19 @@ static unsigned int __ioremap_check_encr
 	return 0;
 }
 
+/*
+ * The EFI runtime services data area is not covered by walk_mem_res(), but must
+ * be mapped encrypted when SEV is active.
+ */
+static void __ioremap_check_other(resource_size_t addr, struct ioremap_desc *desc)
+{
+	if (!sev_active())
+		return;
+
+	if (efi_mem_type(addr) == EFI_RUNTIME_SERVICES_DATA)
+		desc->flags |= IORES_MAP_ENCRYPTED;
+}
+
 static int __ioremap_collect_map_flags(struct resource *res, void *arg)
 {
 	struct ioremap_desc *desc = arg;
@@ -124,6 +137,9 @@ static int __ioremap_collect_map_flags(s
  * To avoid multiple resource walks, this function walks resources marked as
  * IORESOURCE_MEM and IORESOURCE_BUSY and looking for system RAM and/or a
  * resource described not as IORES_DESC_NONE (e.g. IORES_DESC_ACPI_TABLES).
+ *
+ * After that, deal with misc other ranges in __ioremap_check_other() which do
+ * not fall into the above category.
  */
 static void __ioremap_check_mem(resource_size_t addr, unsigned long size,
 				struct ioremap_desc *desc)
@@ -135,6 +151,8 @@ static void __ioremap_check_mem(resource
 	memset(desc, 0, sizeof(struct ioremap_desc));
 
 	walk_mem_res(start, end, desc, __ioremap_collect_map_flags);
+
+	__ioremap_check_other(addr, desc);
 }
 
 /*