[PATCH v11 0/7] Basic recovery for machine checks inside SGX

[PATCH v11 0/7] Basic recovery for machine checks inside SGX

[Tony Luck]

Boris,

I took this series out of lkml/x86 for a few revisions, I think
the last one posted to lkml was v5. So much has changed since then
that it might be easier to just look at this as if it were v1 and
ignore the earlier history.

First four patches add infrastructure within the SGX code to
track enclave pages (because these pages don't have a "struct
page" as they aren't directly accessible by Linux). All have
"Reviewed-by" tags from Jarkko (SGX maintainer).

Patch 5 hooks into memory_failure() to invoke recovery if
the physical address is in enclave space. This has a
"Reviewed-by" tag from Naoya Horiguchi the maintainer for
mm/memory-failure.c

Patch 6 is a hook into the error injection code and addition
to the error injection documentation explaining extra steps
needed to inject into SGX enclave memory.

Patch 7 is a hook into GHES error reporting path to recognize
that SGX enclave addresses are valid and need processing.

-Tony

Tony Luck (7):
  x86/sgx: Add new sgx_epc_page flag bit to mark free pages
  x86/sgx: Add infrastructure to identify SGX EPC pages
  x86/sgx: Initial poison handling for dirty and free pages
  x86/sgx: Add SGX infrastructure to recover from poison
  x86/sgx: Hook arch_memory_failure() into mainline code
  x86/sgx: Add hook to error injection address validation
  x86/sgx: Add check for SGX pages to ghes_do_memory_failure()

 .../firmware-guide/acpi/apei/einj.rst         |  19 +++
 arch/x86/Kconfig                              |   1 +
 arch/x86/include/asm/processor.h              |   8 ++
 arch/x86/include/asm/set_memory.h             |   4 +
 arch/x86/kernel/cpu/sgx/main.c                | 113 +++++++++++++++++-
 arch/x86/kernel/cpu/sgx/sgx.h                 |   7 +-
 drivers/acpi/apei/einj.c                      |   3 +-
 drivers/acpi/apei/ghes.c                      |   2 +-
 include/linux/mm.h                            |  13 ++
 mm/memory-failure.c                           |  19 ++-
 10 files changed, 179 insertions(+), 10 deletions(-)


base-commit: 3906fe9bb7f1a2c8667ae54e967dc8690824f4ea
-- 
2.31.1

[PATCH v11 1/7] x86/sgx: Add new sgx_epc_page flag bit to mark free pages

[Tony Luck]

SGX EPC pages go through the following life cycle:

        DIRTY ---> FREE ---> IN-USE --\
                    ^                 |
                    \-----------------/

Recovery action for poison for a DIRTY or FREE page is simple. Just
make sure never to allocate the page. IN-USE pages need some extra
handling.

Add a new flag bit SGX_EPC_PAGE_IS_FREE that is set when a page
is added to a free list and cleared when the page is allocated.

Notes:

1) These transitions are made while holding the node->lock so that
   future code that checks the flags while holding the node->lock
   can be sure that if the SGX_EPC_PAGE_IS_FREE bit is set, then the
   page is on the free list.

2) Initially while the pages are on the dirty list the
   SGX_EPC_PAGE_IS_FREE bit is cleared.

Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
---
 arch/x86/kernel/cpu/sgx/main.c | 2 ++
 arch/x86/kernel/cpu/sgx/sgx.h  | 3 +++
 2 files changed, 5 insertions(+)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 63d3de02bbcc..825aa91516c8 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -472,6 +472,7 @@ static struct sgx_epc_page *__sgx_alloc_epc_page_from_node(int nid)
 	page = list_first_entry(&node->free_page_list, struct sgx_epc_page, list);
 	list_del_init(&page->list);
 	sgx_nr_free_pages--;
+	page->flags = 0;
 
 	spin_unlock(&node->lock);
 
@@ -626,6 +627,7 @@ void sgx_free_epc_page(struct sgx_epc_page *page)
 
 	list_add_tail(&page->list, &node->free_page_list);
 	sgx_nr_free_pages++;
+	page->flags = SGX_EPC_PAGE_IS_FREE;
 
 	spin_unlock(&node->lock);
 }
diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
index 4628acec0009..5906471156c5 100644
--- a/arch/x86/kernel/cpu/sgx/sgx.h
+++ b/arch/x86/kernel/cpu/sgx/sgx.h
@@ -26,6 +26,9 @@
 /* Pages, which are being tracked by the page reclaimer. */
 #define SGX_EPC_PAGE_RECLAIMER_TRACKED	BIT(0)
 
+/* Pages on free list */
+#define SGX_EPC_PAGE_IS_FREE		BIT(1)
+
 struct sgx_epc_page {
 	unsigned int section;
 	unsigned int flags;
-- 
2.31.1

[PATCH v11 2/7] x86/sgx: Add infrastructure to identify SGX EPC pages

[Tony Luck]

X86 machine check architecture reports a physical address when there
is a memory error. Handling that error requires a method to determine
whether the physical address reported is in any of the areas reserved
for EPC pages by BIOS.

SGX EPC pages do not have Linux "struct page" associated with them.

Keep track of the mapping from ranges of EPC pages to the sections
that contain them using an xarray. N.B. adds CONFIG_XARRAY_MULTI to
the SGX dependecies. So "select" that in arch/x86/Kconfig for X86/SGX.

Create a function arch_is_platform_page() that simply reports whether an
address is an EPC page for use elsewhere in the kernel. The ACPI error
injection code needs this function and is typically built as a module,
so export it.

Note that arch_is_platform_page() will be slower than other similar
"what type is this page" functions that can simply check bits in the
"struct page".  If there is some future performance critical user of
this function it may need to be implemented in a more efficient way.

Note also that the current implementation of xarray allocates a few
hundred kilobytes for this usage on a system with 4GB of SGX EPC memory
configured. This isn't ideal, but worth it for the code simplicity.

Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
---
 arch/x86/Kconfig               | 1 +
 arch/x86/kernel/cpu/sgx/main.c | 9 +++++++++
 2 files changed, 10 insertions(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index d9830e7e1060..b3b5b5a31f89 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1902,6 +1902,7 @@ config X86_SGX
 	select SRCU
 	select MMU_NOTIFIER
 	select NUMA_KEEP_MEMINFO if NUMA
+	select XARRAY_MULTI
 	help
 	  Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
 	  that can be used by applications to set aside private regions of code
diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 825aa91516c8..5c02cffdabc8 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -20,6 +20,7 @@ struct sgx_epc_section sgx_epc_sections[SGX_MAX_EPC_SECTIONS];
 static int sgx_nr_epc_sections;
 static struct task_struct *ksgxd_tsk;
 static DECLARE_WAIT_QUEUE_HEAD(ksgxd_waitq);
+static DEFINE_XARRAY(sgx_epc_address_space);
 
 /*
  * These variables are part of the state of the reclaimer, and must be accessed
@@ -650,6 +651,8 @@ static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size,
 	}
 
 	section->phys_addr = phys_addr;
+	xa_store_range(&sgx_epc_address_space, section->phys_addr,
+		       phys_addr + size - 1, section, GFP_KERNEL);
 
 	for (i = 0; i < nr_pages; i++) {
 		section->pages[i].section = index;
@@ -661,6 +664,12 @@ static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size,
 	return true;
 }
 
+bool arch_is_platform_page(u64 paddr)
+{
+	return !!xa_load(&sgx_epc_address_space, paddr);
+}
+EXPORT_SYMBOL_GPL(arch_is_platform_page);
+
 /**
  * A section metric is concatenated in a way that @low bits 12-31 define the
  * bits 12-31 of the metric and @high bits 0-19 define the bits 32-51 of the
-- 
2.31.1

[PATCH v11 3/7] x86/sgx: Initial poison handling for dirty and free pages

[Tony Luck]

A memory controller patrol scrubber can report poison in a page
that isn't currently being used.

Add "poison" field in the sgx_epc_page that can be set for an
sgx_epc_page. Check for it:
1) When sanitizing dirty pages
2) When freeing epc pages

Poison is a new field separated from flags to avoid having to make all
updates to flags atomic, or integrate poison state changes into some
other locking scheme to protect flags (Currently just sgx_reclaimer_lock
which protects the SGX_EPC_PAGE_RECLAIMER_TRACKED bit in page->flags).

In both cases place the poisoned page on a per-node list of poisoned
epc pages to make sure it will not be reallocated.

Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
---
 arch/x86/kernel/cpu/sgx/main.c | 26 +++++++++++++++++++++++++-
 arch/x86/kernel/cpu/sgx/sgx.h  |  4 +++-
 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 5c02cffdabc8..e5fcb8354bcc 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -62,6 +62,24 @@ static void __sgx_sanitize_pages(struct list_head *dirty_page_list)
 
 		page = list_first_entry(dirty_page_list, struct sgx_epc_page, list);
 
+		/*
+		 * Checking page->poison without holding the node->lock
+		 * is racy, but losing the race (i.e. poison is set just
+		 * after the check) just means __eremove() will be uselessly
+		 * called for a page that sgx_free_epc_page() will put onto
+		 * the node->sgx_poison_page_list later.
+		 */
+		if (page->poison) {
+			struct sgx_epc_section *section = &sgx_epc_sections[page->section];
+			struct sgx_numa_node *node = section->node;
+
+			spin_lock(&node->lock);
+			list_move(&page->list, &node->sgx_poison_page_list);
+			spin_unlock(&node->lock);
+
+			continue;
+		}
+
 		ret = __eremove(sgx_get_epc_virt_addr(page));
 		if (!ret) {
 			/*
@@ -626,7 +644,11 @@ void sgx_free_epc_page(struct sgx_epc_page *page)
 
 	spin_lock(&node->lock);
 
-	list_add_tail(&page->list, &node->free_page_list);
+	page->owner = NULL;
+	if (page->poison)
+		list_add(&page->list, &node->sgx_poison_page_list);
+	else
+		list_add_tail(&page->list, &node->free_page_list);
 	sgx_nr_free_pages++;
 	page->flags = SGX_EPC_PAGE_IS_FREE;
 
@@ -658,6 +680,7 @@ static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size,
 		section->pages[i].section = index;
 		section->pages[i].flags = 0;
 		section->pages[i].owner = NULL;
+		section->pages[i].poison = 0;
 		list_add_tail(&section->pages[i].list, &sgx_dirty_page_list);
 	}
 
@@ -724,6 +747,7 @@ static bool __init sgx_page_cache_init(void)
 		if (!node_isset(nid, sgx_numa_mask)) {
 			spin_lock_init(&sgx_numa_nodes[nid].lock);
 			INIT_LIST_HEAD(&sgx_numa_nodes[nid].free_page_list);
+			INIT_LIST_HEAD(&sgx_numa_nodes[nid].sgx_poison_page_list);
 			node_set(nid, sgx_numa_mask);
 		}
 
diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
index 5906471156c5..9ec3136c7800 100644
--- a/arch/x86/kernel/cpu/sgx/sgx.h
+++ b/arch/x86/kernel/cpu/sgx/sgx.h
@@ -31,7 +31,8 @@
 
 struct sgx_epc_page {
 	unsigned int section;
-	unsigned int flags;
+	u16 flags;
+	u16 poison;
 	struct sgx_encl_page *owner;
 	struct list_head list;
 };
@@ -42,6 +43,7 @@ struct sgx_epc_page {
  */
 struct sgx_numa_node {
 	struct list_head free_page_list;
+	struct list_head sgx_poison_page_list;
 	spinlock_t lock;
 };
 
-- 
2.31.1

[PATCH v11 4/7] x86/sgx: Add SGX infrastructure to recover from poison

[Tony Luck]

Provide a recovery function sgx_memory_failure(). If the poison was
consumed synchronously then send a SIGBUS. Note that the virtual
address of the access is not included with the SIGBUS as is the case
for poison outside of SGX enclaves. This doesn't matter as addresses
of code/data inside an enclave is of little to no use to code executing
outside the (now dead) enclave.

Poison found in a free page results in the page being moved from the
free list to the per-node poison page list.

Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
---
 arch/x86/kernel/cpu/sgx/main.c | 76 ++++++++++++++++++++++++++++++++++
 1 file changed, 76 insertions(+)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index e5fcb8354bcc..231c494dfd40 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -693,6 +693,82 @@ bool arch_is_platform_page(u64 paddr)
 }
 EXPORT_SYMBOL_GPL(arch_is_platform_page);
 
+static struct sgx_epc_page *sgx_paddr_to_page(u64 paddr)
+{
+	struct sgx_epc_section *section;
+
+	section = xa_load(&sgx_epc_address_space, paddr);
+	if (!section)
+		return NULL;
+
+	return &section->pages[PFN_DOWN(paddr - section->phys_addr)];
+}
+
+/*
+ * Called in process context to handle a hardware reported
+ * error in an SGX EPC page.
+ * If the MF_ACTION_REQUIRED bit is set in flags, then the
+ * context is the task that consumed the poison data. Otherwise
+ * this is called from a kernel thread unrelated to the page.
+ */
+int arch_memory_failure(unsigned long pfn, int flags)
+{
+	struct sgx_epc_page *page = sgx_paddr_to_page(pfn << PAGE_SHIFT);
+	struct sgx_epc_section *section;
+	struct sgx_numa_node *node;
+
+	/*
+	 * mm/memory-failure.c calls this routine for all errors
+	 * where there isn't a "struct page" for the address. But that
+	 * includes other address ranges besides SGX.
+	 */
+	if (!page)
+		return -ENXIO;
+
+	/*
+	 * If poison was consumed synchronously. Send a SIGBUS to
+	 * the task. Hardware has already exited the SGX enclave and
+	 * will not allow re-entry to an enclave that has a memory
+	 * error. The signal may help the task understand why the
+	 * enclave is broken.
+	 */
+	if (flags & MF_ACTION_REQUIRED)
+		force_sig(SIGBUS);
+
+	section = &sgx_epc_sections[page->section];
+	node = section->node;
+
+	spin_lock(&node->lock);
+
+	/* Already poisoned? Nothing more to do */
+	if (page->poison)
+		goto out;
+
+	page->poison = 1;
+
+	/*
+	 * If the page is on a free list, move it to the per-node
+	 * poison page list.
+	 */
+	if (page->flags & SGX_EPC_PAGE_IS_FREE) {
+		list_move(&page->list, &node->sgx_poison_page_list);
+		goto out;
+	}
+
+	/*
+	 * TBD: Add additional plumbing to enable pre-emptive
+	 * action for asynchronous poison notification. Until
+	 * then just hope that the poison:
+	 * a) is not accessed - sgx_free_epc_page() will deal with it
+	 *    when the user gives it back
+	 * b) results in a recoverable machine check rather than
+	 *    a fatal one
+	 */
+out:
+	spin_unlock(&node->lock);
+	return 0;
+}
+
 /**
  * A section metric is concatenated in a way that @low bits 12-31 define the
  * bits 12-31 of the metric and @high bits 0-19 define the bits 32-51 of the
-- 
2.31.1

[PATCH v11 5/7] x86/sgx: Hook arch_memory_failure() into mainline code

[Tony Luck]

Add a call inside memory_failure() to call the arch specific code
to check if the address is an SGX EPC page and handle it.

Note the SGX EPC pages do not have a "struct page" entry, so the hook
goes in at the same point as the device mapping hook.

Pull the call to acquire the mutex earlier so the SGX errors are also
protected.

Make set_mce_nospec() skip SGX pages when trying to adjust
the 1:1 map.

Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Tested-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
---
 arch/x86/include/asm/processor.h  |  8 ++++++++
 arch/x86/include/asm/set_memory.h |  4 ++++
 include/linux/mm.h                | 13 +++++++++++++
 mm/memory-failure.c               | 19 +++++++++++++------
 4 files changed, 38 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 9ad2acaaae9b..4865f2860a4f 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -853,4 +853,12 @@ enum mds_mitigations {
 	MDS_MITIGATION_VMWERV,
 };
 
+#ifdef CONFIG_X86_SGX
+int arch_memory_failure(unsigned long pfn, int flags);
+#define arch_memory_failure arch_memory_failure
+
+bool arch_is_platform_page(u64 paddr);
+#define arch_is_platform_page arch_is_platform_page
+#endif
+
 #endif /* _ASM_X86_PROCESSOR_H */
diff --git a/arch/x86/include/asm/set_memory.h b/arch/x86/include/asm/set_memory.h
index 43fa081a1adb..ce8dd215f5b3 100644
--- a/arch/x86/include/asm/set_memory.h
+++ b/arch/x86/include/asm/set_memory.h
@@ -2,6 +2,7 @@
 #ifndef _ASM_X86_SET_MEMORY_H
 #define _ASM_X86_SET_MEMORY_H
 
+#include <linux/mm.h>
 #include <asm/page.h>
 #include <asm-generic/set_memory.h>
 
@@ -98,6 +99,9 @@ static inline int set_mce_nospec(unsigned long pfn, bool unmap)
 	unsigned long decoy_addr;
 	int rc;
 
+	/* SGX pages are not in the 1:1 map */
+	if (arch_is_platform_page(pfn << PAGE_SHIFT))
+		return 0;
 	/*
 	 * We would like to just call:
 	 *      set_memory_XX((unsigned long)pfn_to_kaddr(pfn), 1);
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 73a52aba448f..0aa48b238db2 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3124,6 +3124,19 @@ extern void shake_page(struct page *p);
 extern atomic_long_t num_poisoned_pages __read_mostly;
 extern int soft_offline_page(unsigned long pfn, int flags);
 
+#ifndef arch_memory_failure
+static inline int arch_memory_failure(unsigned long pfn, int flags)
+{
+	return -ENXIO;
+}
+#endif
+
+#ifndef arch_is_platform_page
+static inline bool arch_is_platform_page(u64 paddr)
+{
+	return false;
+}
+#endif
 
 /*
  * Error handlers for various types of pages.
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 3e6449f2102a..b1cbf9845c19 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1632,21 +1632,28 @@ int memory_failure(unsigned long pfn, int flags)
 	if (!sysctl_memory_failure_recovery)
 		panic("Memory failure on page %lx", pfn);
 
+	mutex_lock(&mf_mutex);
+
 	p = pfn_to_online_page(pfn);
 	if (!p) {
+		res = arch_memory_failure(pfn, flags);
+		if (res == 0)
+			goto unlock_mutex;
+
 		if (pfn_valid(pfn)) {
 			pgmap = get_dev_pagemap(pfn, NULL);
-			if (pgmap)
-				return memory_failure_dev_pagemap(pfn, flags,
-								  pgmap);
+			if (pgmap) {
+				res = memory_failure_dev_pagemap(pfn, flags,
+								 pgmap);
+				goto unlock_mutex;
+			}
 		}
 		pr_err("Memory failure: %#lx: memory outside kernel control\n",
 			pfn);
-		return -ENXIO;
+		res = -ENXIO;
+		goto unlock_mutex;
 	}
 
-	mutex_lock(&mf_mutex);
-
 try_again:
 	if (PageHuge(p)) {
 		res = memory_failure_hugetlb(pfn, flags);
-- 
2.31.1

[PATCH v11 6/7] x86/sgx: Add hook to error injection address validation

[Tony Luck]

SGX reserved memory does not appear in the standard address maps.

Add hook to call into the SGX code to check if an address is located
in SGX memory.

There are other challenges in injecting errors into SGX. Update the
documentation with a sequence of operations to inject.

Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
---
 .../firmware-guide/acpi/apei/einj.rst         | 19 +++++++++++++++++++
 drivers/acpi/apei/einj.c                      |  3 ++-
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/Documentation/firmware-guide/acpi/apei/einj.rst b/Documentation/firmware-guide/acpi/apei/einj.rst
index c042176e1707..55e2331a6438 100644
--- a/Documentation/firmware-guide/acpi/apei/einj.rst
+++ b/Documentation/firmware-guide/acpi/apei/einj.rst
@@ -181,5 +181,24 @@ You should see something like this in dmesg::
   [22715.834759] EDAC sbridge MC3: PROCESSOR 0:306e7 TIME 1422553404 SOCKET 0 APIC 0
   [22716.616173] EDAC MC3: 1 CE memory read error on CPU_SrcID#0_Channel#0_DIMM#0 (channel:0 slot:0 page:0x12345 offset:0x0 grain:32 syndrome:0x0 -  area:DRAM err_code:0001:0090 socket:0 channel_mask:1 rank:0)
 
+Special notes for injection into SGX enclaves:
+
+There may be a separate BIOS setup option to enable SGX injection.
+
+The injection process consists of setting some special memory controller
+trigger that will inject the error on the next write to the target
+address. But the h/w prevents any software outside of an SGX enclave
+from accessing enclave pages (even BIOS SMM mode).
+
+The following sequence can be used:
+  1) Determine physical address of enclave page
+  2) Use "notrigger=1" mode to inject (this will setup
+     the injection address, but will not actually inject)
+  3) Enter the enclave
+  4) Store data to the virtual address matching physical address from step 1
+  5) Execute CLFLUSH for that virtual address
+  6) Spin delay for 250ms
+  7) Read from the virtual address. This will trigger the error
+
 For more information about EINJ, please refer to ACPI specification
 version 4.0, section 17.5 and ACPI 5.0, section 18.6.
diff --git a/drivers/acpi/apei/einj.c b/drivers/acpi/apei/einj.c
index 2882450c443e..67c335baad52 100644
--- a/drivers/acpi/apei/einj.c
+++ b/drivers/acpi/apei/einj.c
@@ -544,7 +544,8 @@ static int einj_error_inject(u32 type, u32 flags, u64 param1, u64 param2,
 	    ((region_intersects(base_addr, size, IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE)
 				!= REGION_INTERSECTS) &&
 	     (region_intersects(base_addr, size, IORESOURCE_MEM, IORES_DESC_PERSISTENT_MEMORY)
-				!= REGION_INTERSECTS)))
+				!= REGION_INTERSECTS) &&
+	     !arch_is_platform_page(base_addr)))
 		return -EINVAL;
 
 inject:
-- 
2.31.1

[PATCH v11 7/7] x86/sgx: Add check for SGX pages to ghes_do_memory_failure()

[Tony Luck]

SGX EPC pages do not have a "struct page" associated with them so the
pfn_valid() sanity check fails and results in a warning message to
the console.

Add an additional check to skip the warning if the address of the error
is in an SGX EPC page.

Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
---
 drivers/acpi/apei/ghes.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index 0c8330ed1ffd..0c5c9acc6254 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -449,7 +449,7 @@ static bool ghes_do_memory_failure(u64 physical_addr, int flags)
 		return false;
 
 	pfn = PHYS_PFN(physical_addr);
-	if (!pfn_valid(pfn)) {
+	if (!pfn_valid(pfn) && !arch_is_platform_page(physical_addr)) {
 		pr_warn_ratelimited(FW_WARN GHES_PFX
 		"Invalid address in generic error data: %#llx\n",
 		physical_addr);
-- 
2.31.1

Re: [PATCH v11 7/7] x86/sgx: Add check for SGX pages to ghes_do_memory_failure()

[Rafael J. Wysocki]

On Wed, Oct 27, 2021 at 12:01 AM Tony Luck <tony.luck@intel.com> wrote:
>
> SGX EPC pages do not have a "struct page" associated with them so the
> pfn_valid() sanity check fails and results in a warning message to
> the console.
>
> Add an additional check to skip the warning if the address of the error
> is in an SGX EPC page.
>
> Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
> Tested-by: Reinette Chatre <reinette.chatre@intel.com>
> Signed-off-by: Tony Luck <tony.luck@intel.com>

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

> ---
>  drivers/acpi/apei/ghes.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
> index 0c8330ed1ffd..0c5c9acc6254 100644
> --- a/drivers/acpi/apei/ghes.c
> +++ b/drivers/acpi/apei/ghes.c
> @@ -449,7 +449,7 @@ static bool ghes_do_memory_failure(u64 physical_addr, int flags)
>                 return false;
>
>         pfn = PHYS_PFN(physical_addr);
> -       if (!pfn_valid(pfn)) {
> +       if (!pfn_valid(pfn) && !arch_is_platform_page(physical_addr)) {
>                 pr_warn_ratelimited(FW_WARN GHES_PFX
>                 "Invalid address in generic error data: %#llx\n",
>                 physical_addr);
> --
> 2.31.1
>

[tip: x86/sgx] x86/sgx: Add check for SGX pages to ghes_do_memory_failure()

[tip-bot2 for Tony Luck]

The following commit has been merged into the x86/sgx branch of tip:

Commit-ID:     3ad6fd77a2d62e8f4465b429b65805eaf88e1b9e
Gitweb:        https://git.kernel.org/tip/3ad6fd77a2d62e8f4465b429b65805eaf88e1b9e
Author:        Tony Luck <tony.luck@intel.com>
AuthorDate:    Tue, 26 Oct 2021 15:00:50 -07:00
Committer:     Dave Hansen <dave.hansen@linux.intel.com>
CommitterDate: Mon, 15 Nov 2021 11:13:16 -08:00

x86/sgx: Add check for SGX pages to ghes_do_memory_failure()

SGX EPC pages do not have a "struct page" associated with them so the
pfn_valid() sanity check fails and results in a warning message to
the console.

Add an additional check to skip the warning if the address of the error
is in an SGX EPC page.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lkml.kernel.org/r/20211026220050.697075-8-tony.luck@intel.com
---
 drivers/acpi/apei/ghes.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index 0c8330e..0c5c9ac 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -449,7 +449,7 @@ static bool ghes_do_memory_failure(u64 physical_addr, int flags)
 		return false;
 
 	pfn = PHYS_PFN(physical_addr);
-	if (!pfn_valid(pfn)) {
+	if (!pfn_valid(pfn) && !arch_is_platform_page(physical_addr)) {
 		pr_warn_ratelimited(FW_WARN GHES_PFX
 		"Invalid address in generic error data: %#llx\n",
 		physical_addr);

[tip: x86/sgx] x86/sgx: Add hook to error injection address validation

[tip-bot2 for Tony Luck]

The following commit has been merged into the x86/sgx branch of tip:

Commit-ID:     c6acb1e7bf4656b9434335c72b8245cc84575fde
Gitweb:        https://git.kernel.org/tip/c6acb1e7bf4656b9434335c72b8245cc84575fde
Author:        Tony Luck <tony.luck@intel.com>
AuthorDate:    Tue, 26 Oct 2021 15:00:49 -07:00
Committer:     Dave Hansen <dave.hansen@linux.intel.com>
CommitterDate: Mon, 15 Nov 2021 11:13:16 -08:00

x86/sgx: Add hook to error injection address validation

SGX reserved memory does not appear in the standard address maps.

Add hook to call into the SGX code to check if an address is located
in SGX memory.

There are other challenges in injecting errors into SGX. Update the
documentation with a sequence of operations to inject.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lkml.kernel.org/r/20211026220050.697075-7-tony.luck@intel.com
---
 Documentation/firmware-guide/acpi/apei/einj.rst | 19 ++++++++++++++++-
 drivers/acpi/apei/einj.c                        |  3 ++-
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/Documentation/firmware-guide/acpi/apei/einj.rst b/Documentation/firmware-guide/acpi/apei/einj.rst
index c042176..55e2331 100644
--- a/Documentation/firmware-guide/acpi/apei/einj.rst
+++ b/Documentation/firmware-guide/acpi/apei/einj.rst
@@ -181,5 +181,24 @@ You should see something like this in dmesg::
   [22715.834759] EDAC sbridge MC3: PROCESSOR 0:306e7 TIME 1422553404 SOCKET 0 APIC 0
   [22716.616173] EDAC MC3: 1 CE memory read error on CPU_SrcID#0_Channel#0_DIMM#0 (channel:0 slot:0 page:0x12345 offset:0x0 grain:32 syndrome:0x0 -  area:DRAM err_code:0001:0090 socket:0 channel_mask:1 rank:0)
 
+Special notes for injection into SGX enclaves:
+
+There may be a separate BIOS setup option to enable SGX injection.
+
+The injection process consists of setting some special memory controller
+trigger that will inject the error on the next write to the target
+address. But the h/w prevents any software outside of an SGX enclave
+from accessing enclave pages (even BIOS SMM mode).
+
+The following sequence can be used:
+  1) Determine physical address of enclave page
+  2) Use "notrigger=1" mode to inject (this will setup
+     the injection address, but will not actually inject)
+  3) Enter the enclave
+  4) Store data to the virtual address matching physical address from step 1
+  5) Execute CLFLUSH for that virtual address
+  6) Spin delay for 250ms
+  7) Read from the virtual address. This will trigger the error
+
 For more information about EINJ, please refer to ACPI specification
 version 4.0, section 17.5 and ACPI 5.0, section 18.6.
diff --git a/drivers/acpi/apei/einj.c b/drivers/acpi/apei/einj.c
index edb2622..95cc2a9 100644
--- a/drivers/acpi/apei/einj.c
+++ b/drivers/acpi/apei/einj.c
@@ -545,7 +545,8 @@ static int einj_error_inject(u32 type, u32 flags, u64 param1, u64 param2,
 	    ((region_intersects(base_addr, size, IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE)
 				!= REGION_INTERSECTS) &&
 	     (region_intersects(base_addr, size, IORESOURCE_MEM, IORES_DESC_PERSISTENT_MEMORY)
-				!= REGION_INTERSECTS)))
+				!= REGION_INTERSECTS) &&
+	     !arch_is_platform_page(base_addr)))
 		return -EINVAL;
 
 inject:

[tip: x86/sgx] x86/sgx: Hook arch_memory_failure() into mainline code

[tip-bot2 for Tony Luck]

The following commit has been merged into the x86/sgx branch of tip:

Commit-ID:     03b122da74b22fbe7cd98184fa5657a9ce13970c
Gitweb:        https://git.kernel.org/tip/03b122da74b22fbe7cd98184fa5657a9ce13970c
Author:        Tony Luck <tony.luck@intel.com>
AuthorDate:    Tue, 26 Oct 2021 15:00:48 -07:00
Committer:     Dave Hansen <dave.hansen@linux.intel.com>
CommitterDate: Mon, 15 Nov 2021 11:13:16 -08:00

x86/sgx: Hook arch_memory_failure() into mainline code

Add a call inside memory_failure() to call the arch specific code
to check if the address is an SGX EPC page and handle it.

Note the SGX EPC pages do not have a "struct page" entry, so the hook
goes in at the same point as the device mapping hook.

Pull the call to acquire the mutex earlier so the SGX errors are also
protected.

Make set_mce_nospec() skip SGX pages when trying to adjust
the 1:1 map.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Tested-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lkml.kernel.org/r/20211026220050.697075-6-tony.luck@intel.com
---
 arch/x86/include/asm/processor.h  |  8 ++++++++
 arch/x86/include/asm/set_memory.h |  4 ++++
 include/linux/mm.h                | 13 +++++++++++++
 mm/memory-failure.c               | 19 +++++++++++++------
 4 files changed, 38 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 355d38c..2c5f12a 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -855,4 +855,12 @@ enum mds_mitigations {
 	MDS_MITIGATION_VMWERV,
 };
 
+#ifdef CONFIG_X86_SGX
+int arch_memory_failure(unsigned long pfn, int flags);
+#define arch_memory_failure arch_memory_failure
+
+bool arch_is_platform_page(u64 paddr);
+#define arch_is_platform_page arch_is_platform_page
+#endif
+
 #endif /* _ASM_X86_PROCESSOR_H */
diff --git a/arch/x86/include/asm/set_memory.h b/arch/x86/include/asm/set_memory.h
index 8726175..ff0f2d9 100644
--- a/arch/x86/include/asm/set_memory.h
+++ b/arch/x86/include/asm/set_memory.h
@@ -2,6 +2,7 @@
 #ifndef _ASM_X86_SET_MEMORY_H
 #define _ASM_X86_SET_MEMORY_H
 
+#include <linux/mm.h>
 #include <asm/page.h>
 #include <asm-generic/set_memory.h>
 
@@ -99,6 +100,9 @@ static inline int set_mce_nospec(unsigned long pfn, bool unmap)
 	unsigned long decoy_addr;
 	int rc;
 
+	/* SGX pages are not in the 1:1 map */
+	if (arch_is_platform_page(pfn << PAGE_SHIFT))
+		return 0;
 	/*
 	 * We would like to just call:
 	 *      set_memory_XX((unsigned long)pfn_to_kaddr(pfn), 1);
diff --git a/include/linux/mm.h b/include/linux/mm.h
index a7e4a9e..57f1aa2 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3231,6 +3231,19 @@ extern void shake_page(struct page *p);
 extern atomic_long_t num_poisoned_pages __read_mostly;
 extern int soft_offline_page(unsigned long pfn, int flags);
 
+#ifndef arch_memory_failure
+static inline int arch_memory_failure(unsigned long pfn, int flags)
+{
+	return -ENXIO;
+}
+#endif
+
+#ifndef arch_is_platform_page
+static inline bool arch_is_platform_page(u64 paddr)
+{
+	return false;
+}
+#endif
 
 /*
  * Error handlers for various types of pages.
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 07c875f..fddee33 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1651,21 +1651,28 @@ int memory_failure(unsigned long pfn, int flags)
 	if (!sysctl_memory_failure_recovery)
 		panic("Memory failure on page %lx", pfn);
 
+	mutex_lock(&mf_mutex);
+
 	p = pfn_to_online_page(pfn);
 	if (!p) {
+		res = arch_memory_failure(pfn, flags);
+		if (res == 0)
+			goto unlock_mutex;
+
 		if (pfn_valid(pfn)) {
 			pgmap = get_dev_pagemap(pfn, NULL);
-			if (pgmap)
-				return memory_failure_dev_pagemap(pfn, flags,
-								  pgmap);
+			if (pgmap) {
+				res = memory_failure_dev_pagemap(pfn, flags,
+								 pgmap);
+				goto unlock_mutex;
+			}
 		}
 		pr_err("Memory failure: %#lx: memory outside kernel control\n",
 			pfn);
-		return -ENXIO;
+		res = -ENXIO;
+		goto unlock_mutex;
 	}
 
-	mutex_lock(&mf_mutex);
-
 try_again:
 	if (PageHuge(p)) {
 		res = memory_failure_hugetlb(pfn, flags);

[tip: x86/sgx] x86/sgx: Add SGX infrastructure to recover from poison

[tip-bot2 for Tony Luck]

The following commit has been merged into the x86/sgx branch of tip:

Commit-ID:     a495cbdffa30558b34f3c95555cecc4fd9688039
Gitweb:        https://git.kernel.org/tip/a495cbdffa30558b34f3c95555cecc4fd9688039
Author:        Tony Luck <tony.luck@intel.com>
AuthorDate:    Tue, 26 Oct 2021 15:00:47 -07:00
Committer:     Dave Hansen <dave.hansen@linux.intel.com>
CommitterDate: Mon, 15 Nov 2021 11:13:16 -08:00

x86/sgx: Add SGX infrastructure to recover from poison

Provide a recovery function sgx_memory_failure(). If the poison was
consumed synchronously then send a SIGBUS. Note that the virtual
address of the access is not included with the SIGBUS as is the case
for poison outside of SGX enclaves. This doesn't matter as addresses
of code/data inside an enclave is of little to no use to code executing
outside the (now dead) enclave.

Poison found in a free page results in the page being moved from the
free list to the per-node poison page list.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lkml.kernel.org/r/20211026220050.697075-5-tony.luck@intel.com
---
 arch/x86/kernel/cpu/sgx/main.c | 76 +++++++++++++++++++++++++++++++++-
 1 file changed, 76 insertions(+)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index e5fcb83..231c494 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -693,6 +693,82 @@ bool arch_is_platform_page(u64 paddr)
 }
 EXPORT_SYMBOL_GPL(arch_is_platform_page);
 
+static struct sgx_epc_page *sgx_paddr_to_page(u64 paddr)
+{
+	struct sgx_epc_section *section;
+
+	section = xa_load(&sgx_epc_address_space, paddr);
+	if (!section)
+		return NULL;
+
+	return &section->pages[PFN_DOWN(paddr - section->phys_addr)];
+}
+
+/*
+ * Called in process context to handle a hardware reported
+ * error in an SGX EPC page.
+ * If the MF_ACTION_REQUIRED bit is set in flags, then the
+ * context is the task that consumed the poison data. Otherwise
+ * this is called from a kernel thread unrelated to the page.
+ */
+int arch_memory_failure(unsigned long pfn, int flags)
+{
+	struct sgx_epc_page *page = sgx_paddr_to_page(pfn << PAGE_SHIFT);
+	struct sgx_epc_section *section;
+	struct sgx_numa_node *node;
+
+	/*
+	 * mm/memory-failure.c calls this routine for all errors
+	 * where there isn't a "struct page" for the address. But that
+	 * includes other address ranges besides SGX.
+	 */
+	if (!page)
+		return -ENXIO;
+
+	/*
+	 * If poison was consumed synchronously. Send a SIGBUS to
+	 * the task. Hardware has already exited the SGX enclave and
+	 * will not allow re-entry to an enclave that has a memory
+	 * error. The signal may help the task understand why the
+	 * enclave is broken.
+	 */
+	if (flags & MF_ACTION_REQUIRED)
+		force_sig(SIGBUS);
+
+	section = &sgx_epc_sections[page->section];
+	node = section->node;
+
+	spin_lock(&node->lock);
+
+	/* Already poisoned? Nothing more to do */
+	if (page->poison)
+		goto out;
+
+	page->poison = 1;
+
+	/*
+	 * If the page is on a free list, move it to the per-node
+	 * poison page list.
+	 */
+	if (page->flags & SGX_EPC_PAGE_IS_FREE) {
+		list_move(&page->list, &node->sgx_poison_page_list);
+		goto out;
+	}
+
+	/*
+	 * TBD: Add additional plumbing to enable pre-emptive
+	 * action for asynchronous poison notification. Until
+	 * then just hope that the poison:
+	 * a) is not accessed - sgx_free_epc_page() will deal with it
+	 *    when the user gives it back
+	 * b) results in a recoverable machine check rather than
+	 *    a fatal one
+	 */
+out:
+	spin_unlock(&node->lock);
+	return 0;
+}
+
 /**
  * A section metric is concatenated in a way that @low bits 12-31 define the
  * bits 12-31 of the metric and @high bits 0-19 define the bits 32-51 of the

[tip: x86/sgx] x86/sgx: Add infrastructure to identify SGX EPC pages

[tip-bot2 for Tony Luck]

The following commit has been merged into the x86/sgx branch of tip:

Commit-ID:     40e0e7843e23d164625b9031514f5672f8758bf4
Gitweb:        https://git.kernel.org/tip/40e0e7843e23d164625b9031514f5672f8758bf4
Author:        Tony Luck <tony.luck@intel.com>
AuthorDate:    Tue, 26 Oct 2021 15:00:45 -07:00
Committer:     Dave Hansen <dave.hansen@linux.intel.com>
CommitterDate: Mon, 15 Nov 2021 11:13:16 -08:00

x86/sgx: Add infrastructure to identify SGX EPC pages

X86 machine check architecture reports a physical address when there
is a memory error. Handling that error requires a method to determine
whether the physical address reported is in any of the areas reserved
for EPC pages by BIOS.

SGX EPC pages do not have Linux "struct page" associated with them.

Keep track of the mapping from ranges of EPC pages to the sections
that contain them using an xarray. N.B. adds CONFIG_XARRAY_MULTI to
the SGX dependecies. So "select" that in arch/x86/Kconfig for X86/SGX.

Create a function arch_is_platform_page() that simply reports whether an
address is an EPC page for use elsewhere in the kernel. The ACPI error
injection code needs this function and is typically built as a module,
so export it.

Note that arch_is_platform_page() will be slower than other similar
"what type is this page" functions that can simply check bits in the
"struct page".  If there is some future performance critical user of
this function it may need to be implemented in a more efficient way.

Note also that the current implementation of xarray allocates a few
hundred kilobytes for this usage on a system with 4GB of SGX EPC memory
configured. This isn't ideal, but worth it for the code simplicity.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lkml.kernel.org/r/20211026220050.697075-3-tony.luck@intel.com
---
 arch/x86/Kconfig               |  1 +
 arch/x86/kernel/cpu/sgx/main.c |  9 +++++++++
 2 files changed, 10 insertions(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 95dd1ee..b9281fa 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1917,6 +1917,7 @@ config X86_SGX
 	select SRCU
 	select MMU_NOTIFIER
 	select NUMA_KEEP_MEMINFO if NUMA
+	select XARRAY_MULTI
 	help
 	  Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
 	  that can be used by applications to set aside private regions of code
diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 825aa91..5c02cff 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -20,6 +20,7 @@ struct sgx_epc_section sgx_epc_sections[SGX_MAX_EPC_SECTIONS];
 static int sgx_nr_epc_sections;
 static struct task_struct *ksgxd_tsk;
 static DECLARE_WAIT_QUEUE_HEAD(ksgxd_waitq);
+static DEFINE_XARRAY(sgx_epc_address_space);
 
 /*
  * These variables are part of the state of the reclaimer, and must be accessed
@@ -650,6 +651,8 @@ static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size,
 	}
 
 	section->phys_addr = phys_addr;
+	xa_store_range(&sgx_epc_address_space, section->phys_addr,
+		       phys_addr + size - 1, section, GFP_KERNEL);
 
 	for (i = 0; i < nr_pages; i++) {
 		section->pages[i].section = index;
@@ -661,6 +664,12 @@ static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size,
 	return true;
 }
 
+bool arch_is_platform_page(u64 paddr)
+{
+	return !!xa_load(&sgx_epc_address_space, paddr);
+}
+EXPORT_SYMBOL_GPL(arch_is_platform_page);
+
 /**
  * A section metric is concatenated in a way that @low bits 12-31 define the
  * bits 12-31 of the metric and @high bits 0-19 define the bits 32-51 of the

[tip: x86/sgx] x86/sgx: Initial poison handling for dirty and free pages

[tip-bot2 for Tony Luck]

The following commit has been merged into the x86/sgx branch of tip:

Commit-ID:     992801ae92431761b3d8ec88abd5793d154d34ac
Gitweb:        https://git.kernel.org/tip/992801ae92431761b3d8ec88abd5793d154d34ac
Author:        Tony Luck <tony.luck@intel.com>
AuthorDate:    Tue, 26 Oct 2021 15:00:46 -07:00
Committer:     Dave Hansen <dave.hansen@linux.intel.com>
CommitterDate: Mon, 15 Nov 2021 11:13:16 -08:00

x86/sgx: Initial poison handling for dirty and free pages

A memory controller patrol scrubber can report poison in a page
that isn't currently being used.

Add "poison" field in the sgx_epc_page that can be set for an
sgx_epc_page. Check for it:
1) When sanitizing dirty pages
2) When freeing epc pages

Poison is a new field separated from flags to avoid having to make all
updates to flags atomic, or integrate poison state changes into some
other locking scheme to protect flags (Currently just sgx_reclaimer_lock
which protects the SGX_EPC_PAGE_RECLAIMER_TRACKED bit in page->flags).

In both cases place the poisoned page on a per-node list of poisoned
epc pages to make sure it will not be reallocated.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lkml.kernel.org/r/20211026220050.697075-4-tony.luck@intel.com
---
 arch/x86/kernel/cpu/sgx/main.c | 26 +++++++++++++++++++++++++-
 arch/x86/kernel/cpu/sgx/sgx.h  |  4 +++-
 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 5c02cff..e5fcb83 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -62,6 +62,24 @@ static void __sgx_sanitize_pages(struct list_head *dirty_page_list)
 
 		page = list_first_entry(dirty_page_list, struct sgx_epc_page, list);
 
+		/*
+		 * Checking page->poison without holding the node->lock
+		 * is racy, but losing the race (i.e. poison is set just
+		 * after the check) just means __eremove() will be uselessly
+		 * called for a page that sgx_free_epc_page() will put onto
+		 * the node->sgx_poison_page_list later.
+		 */
+		if (page->poison) {
+			struct sgx_epc_section *section = &sgx_epc_sections[page->section];
+			struct sgx_numa_node *node = section->node;
+
+			spin_lock(&node->lock);
+			list_move(&page->list, &node->sgx_poison_page_list);
+			spin_unlock(&node->lock);
+
+			continue;
+		}
+
 		ret = __eremove(sgx_get_epc_virt_addr(page));
 		if (!ret) {
 			/*
@@ -626,7 +644,11 @@ void sgx_free_epc_page(struct sgx_epc_page *page)
 
 	spin_lock(&node->lock);
 
-	list_add_tail(&page->list, &node->free_page_list);
+	page->owner = NULL;
+	if (page->poison)
+		list_add(&page->list, &node->sgx_poison_page_list);
+	else
+		list_add_tail(&page->list, &node->free_page_list);
 	sgx_nr_free_pages++;
 	page->flags = SGX_EPC_PAGE_IS_FREE;
 
@@ -658,6 +680,7 @@ static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size,
 		section->pages[i].section = index;
 		section->pages[i].flags = 0;
 		section->pages[i].owner = NULL;
+		section->pages[i].poison = 0;
 		list_add_tail(&section->pages[i].list, &sgx_dirty_page_list);
 	}
 
@@ -724,6 +747,7 @@ static bool __init sgx_page_cache_init(void)
 		if (!node_isset(nid, sgx_numa_mask)) {
 			spin_lock_init(&sgx_numa_nodes[nid].lock);
 			INIT_LIST_HEAD(&sgx_numa_nodes[nid].free_page_list);
+			INIT_LIST_HEAD(&sgx_numa_nodes[nid].sgx_poison_page_list);
 			node_set(nid, sgx_numa_mask);
 		}
 
diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
index 5906471..9ec3136 100644
--- a/arch/x86/kernel/cpu/sgx/sgx.h
+++ b/arch/x86/kernel/cpu/sgx/sgx.h
@@ -31,7 +31,8 @@
 
 struct sgx_epc_page {
 	unsigned int section;
-	unsigned int flags;
+	u16 flags;
+	u16 poison;
 	struct sgx_encl_page *owner;
 	struct list_head list;
 };
@@ -42,6 +43,7 @@ struct sgx_epc_page {
  */
 struct sgx_numa_node {
 	struct list_head free_page_list;
+	struct list_head sgx_poison_page_list;
 	spinlock_t lock;
 };
 

[tip: x86/sgx] x86/sgx: Add new sgx_epc_page flag bit to mark free pages

[tip-bot2 for Tony Luck]

The following commit has been merged into the x86/sgx branch of tip:

Commit-ID:     d6d261bded8a57aed4faa12d08a5b193418d3aa4
Gitweb:        https://git.kernel.org/tip/d6d261bded8a57aed4faa12d08a5b193418d3aa4
Author:        Tony Luck <tony.luck@intel.com>
AuthorDate:    Tue, 26 Oct 2021 15:00:44 -07:00
Committer:     Dave Hansen <dave.hansen@linux.intel.com>
CommitterDate: Mon, 15 Nov 2021 11:13:16 -08:00

x86/sgx: Add new sgx_epc_page flag bit to mark free pages

SGX EPC pages go through the following life cycle:

        DIRTY ---> FREE ---> IN-USE --\
                    ^                 |
                    \-----------------/

Recovery action for poison for a DIRTY or FREE page is simple. Just
make sure never to allocate the page. IN-USE pages need some extra
handling.

Add a new flag bit SGX_EPC_PAGE_IS_FREE that is set when a page
is added to a free list and cleared when the page is allocated.

Notes:

1) These transitions are made while holding the node->lock so that
   future code that checks the flags while holding the node->lock
   can be sure that if the SGX_EPC_PAGE_IS_FREE bit is set, then the
   page is on the free list.

2) Initially while the pages are on the dirty list the
   SGX_EPC_PAGE_IS_FREE bit is cleared.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://lkml.kernel.org/r/20211026220050.697075-2-tony.luck@intel.com
---
 arch/x86/kernel/cpu/sgx/main.c | 2 ++
 arch/x86/kernel/cpu/sgx/sgx.h  | 3 +++
 2 files changed, 5 insertions(+)

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 63d3de0..825aa91 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -472,6 +472,7 @@ static struct sgx_epc_page *__sgx_alloc_epc_page_from_node(int nid)
 	page = list_first_entry(&node->free_page_list, struct sgx_epc_page, list);
 	list_del_init(&page->list);
 	sgx_nr_free_pages--;
+	page->flags = 0;
 
 	spin_unlock(&node->lock);
 
@@ -626,6 +627,7 @@ void sgx_free_epc_page(struct sgx_epc_page *page)
 
 	list_add_tail(&page->list, &node->free_page_list);
 	sgx_nr_free_pages++;
+	page->flags = SGX_EPC_PAGE_IS_FREE;
 
 	spin_unlock(&node->lock);
 }
diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h
index 4628ace..5906471 100644
--- a/arch/x86/kernel/cpu/sgx/sgx.h
+++ b/arch/x86/kernel/cpu/sgx/sgx.h
@@ -26,6 +26,9 @@
 /* Pages, which are being tracked by the page reclaimer. */
 #define SGX_EPC_PAGE_RECLAIMER_TRACKED	BIT(0)
 
+/* Pages on free list */
+#define SGX_EPC_PAGE_IS_FREE		BIT(1)
+
 struct sgx_epc_page {
 	unsigned int section;
 	unsigned int flags;