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Date: Wed, 4 Aug 2021 17:52:17 -0700
From: Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@...ux.intel.com>
To: Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
Peter Zijlstra <peterz@...radead.org>,
Andy Lutomirski <luto@...nel.org>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Richard Henderson <rth@...ddle.net>,
Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
James E J Bottomley <James.Bottomley@...senPartnership.com>,
Helge Deller <deller@....de>,
"David S . Miller" <davem@...emloft.net>,
Arnd Bergmann <arnd@...db.de>,
Jonathan Corbet <corbet@....net>,
"Michael S . Tsirkin" <mst@...hat.com>
Cc: Peter H Anvin <hpa@...or.com>, Dave Hansen <dave.hansen@...el.com>,
Tony Luck <tony.luck@...el.com>,
Dan Williams <dan.j.williams@...el.com>,
Andi Kleen <ak@...ux.intel.com>,
Kirill Shutemov <kirill.shutemov@...ux.intel.com>,
Sean Christopherson <seanjc@...gle.com>,
Kuppuswamy Sathyanarayanan <knsathya@...nel.org>,
x86@...nel.org, linux-kernel@...r.kernel.org,
linux-pci@...r.kernel.org, linux-alpha@...r.kernel.org,
linux-mips@...r.kernel.org, linux-parisc@...r.kernel.org,
sparclinux@...r.kernel.org, linux-arch@...r.kernel.org,
linux-doc@...r.kernel.org,
virtualization@...ts.linux-foundation.org
Subject: [PATCH v4 14/15] x86/tdx: Implement ioremap_shared for x86
From: Andi Kleen <ak@...ux.intel.com>
Implement ioremap_shared for x86. In TDX most memory is encrypted,
but some memory that is used to communicate with the host must
be declared shared with special page table attributes and a
special hypercall. Previously all ioremaped memory was declared
shared, but this leads to various BIOS tables and other private
state being shared, which is a security risk.
This patch replaces the unconditional ioremap sharing with an explicit
ioremap_shared that enables sharing.
Signed-off-by: Andi Kleen <ak@...ux.intel.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
---
arch/x86/include/asm/io.h | 3 +++
arch/x86/mm/ioremap.c | 41 ++++++++++++++++++++++++++++++---------
2 files changed, 35 insertions(+), 9 deletions(-)
diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
index 4c9e06a81ebe..51c2c45456bf 100644
--- a/arch/x86/include/asm/io.h
+++ b/arch/x86/include/asm/io.h
@@ -379,6 +379,9 @@ extern void __iomem *ioremap_wc(resource_size_t offset, unsigned long size);
extern void __iomem *ioremap_wt(resource_size_t offset, unsigned long size);
#define ioremap_wt ioremap_wt
+extern void __iomem *ioremap_shared(resource_size_t offset, unsigned long size);
+#define ioremap_shared ioremap_shared
+
extern bool is_early_ioremap_ptep(pte_t *ptep);
#define IO_SPACE_LIMIT 0xffff
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 69a60f240124..74260aaa494b 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -178,7 +178,8 @@ static void __ioremap_check_mem(resource_size_t addr, unsigned long size,
*/
static void __iomem *
__ioremap_caller(resource_size_t phys_addr, unsigned long size,
- enum page_cache_mode pcm, void *caller, bool encrypted)
+ enum page_cache_mode pcm, void *caller, bool encrypted,
+ bool shared)
{
unsigned long offset, vaddr;
resource_size_t last_addr;
@@ -248,7 +249,7 @@ __ioremap_caller(resource_size_t phys_addr, unsigned long size,
prot = PAGE_KERNEL_IO;
if ((io_desc.flags & IORES_MAP_ENCRYPTED) || encrypted)
prot = pgprot_encrypted(prot);
- else if (prot_guest_has(PATTR_GUEST_SHARED_MAPPING_INIT))
+ else if (shared)
prot = pgprot_protected_guest(prot);
switch (pcm) {
@@ -340,7 +341,8 @@ void __iomem *ioremap(resource_size_t phys_addr, unsigned long size)
enum page_cache_mode pcm = _PAGE_CACHE_MODE_UC_MINUS;
return __ioremap_caller(phys_addr, size, pcm,
- __builtin_return_address(0), false);
+ __builtin_return_address(0), false,
+ false);
}
EXPORT_SYMBOL(ioremap);
@@ -373,7 +375,8 @@ void __iomem *ioremap_uc(resource_size_t phys_addr, unsigned long size)
enum page_cache_mode pcm = _PAGE_CACHE_MODE_UC;
return __ioremap_caller(phys_addr, size, pcm,
- __builtin_return_address(0), false);
+ __builtin_return_address(0), false,
+ false);
}
EXPORT_SYMBOL_GPL(ioremap_uc);
@@ -390,10 +393,29 @@ EXPORT_SYMBOL_GPL(ioremap_uc);
void __iomem *ioremap_wc(resource_size_t phys_addr, unsigned long size)
{
return __ioremap_caller(phys_addr, size, _PAGE_CACHE_MODE_WC,
- __builtin_return_address(0), false);
+ __builtin_return_address(0), false,
+ false);
}
EXPORT_SYMBOL(ioremap_wc);
+/**
+ * ioremap_shared - map memory into CPU space shared with host
+ * @phys_addr: bus address of the memory
+ * @size: size of the resource to map
+ *
+ * This version of ioremap ensures that the memory is marked shared
+ * with the host. This is useful for confidential guests.
+ *
+ * Must be freed with iounmap.
+ */
+void __iomem *ioremap_shared(resource_size_t phys_addr, unsigned long size)
+{
+ return __ioremap_caller(phys_addr, size, _PAGE_CACHE_MODE_WC,
+ __builtin_return_address(0), false,
+ prot_guest_has(PATTR_GUEST_SHARED_MAPPING_INIT));
+}
+EXPORT_SYMBOL(ioremap_shared);
+
/**
* ioremap_wt - map memory into CPU space write through
* @phys_addr: bus address of the memory
@@ -407,21 +429,22 @@ EXPORT_SYMBOL(ioremap_wc);
void __iomem *ioremap_wt(resource_size_t phys_addr, unsigned long size)
{
return __ioremap_caller(phys_addr, size, _PAGE_CACHE_MODE_WT,
- __builtin_return_address(0), false);
+ __builtin_return_address(0), false,
+ false);
}
EXPORT_SYMBOL(ioremap_wt);
void __iomem *ioremap_encrypted(resource_size_t phys_addr, unsigned long size)
{
return __ioremap_caller(phys_addr, size, _PAGE_CACHE_MODE_WB,
- __builtin_return_address(0), true);
+ __builtin_return_address(0), true, false);
}
EXPORT_SYMBOL(ioremap_encrypted);
void __iomem *ioremap_cache(resource_size_t phys_addr, unsigned long size)
{
return __ioremap_caller(phys_addr, size, _PAGE_CACHE_MODE_WB,
- __builtin_return_address(0), false);
+ __builtin_return_address(0), false, false);
}
EXPORT_SYMBOL(ioremap_cache);
@@ -430,7 +453,7 @@ void __iomem *ioremap_prot(resource_size_t phys_addr, unsigned long size,
{
return __ioremap_caller(phys_addr, size,
pgprot2cachemode(__pgprot(prot_val)),
- __builtin_return_address(0), false);
+ __builtin_return_address(0), false, false);
}
EXPORT_SYMBOL(ioremap_prot);
--
2.25.1
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