Xen-Devel Archive on lore.kernel.org
 help / color / Atom feed
From: Julien Grall <julien@xen.org>
To: xen-devel@lists.xenproject.org
Cc: alex.bennee@linaro.org, masami.hiramatsu@linaro.org,
	ehem+xen@m5p.com, bertrand.marquis@arm.com,
	andre.przywara@arm.com, Julien Grall <jgrall@amazon.com>,
	Stefano Stabellini <sstabellini@kernel.org>,
	Julien Grall <julien@xen.org>,
	Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>,
	Wei Xu <xuwei5@hisilicon.com>
Subject: [PATCH 2/4] xen/arm: acpi: The fixmap area should always be cleared during failure/unmap
Date: Sat, 26 Sep 2020 21:55:40 +0100
Message-ID: <20200926205542.9261-3-julien@xen.org> (raw)
In-Reply-To: <20200926205542.9261-1-julien@xen.org>

From: Julien Grall <jgrall@amazon.com>

Commit 022387ee1ad3 "xen/arm: mm: Don't open-code Xen PT update in
{set, clear}_fixmap()" enforced that each set_fixmap() should be
paired with a clear_fixmap(). Any failure to follow the model would
result to a platform crash.

Unfortunately, the use of fixmap in the ACPI code was overlooked as it
is calling set_fixmap() but not clear_fixmap().

The function __acpi_os_map_table() is reworked so:
    - We know before the mapping whether the fixmap region is big
    enough for the mapping.
    - It will fail if the fixmap is always inuse.

The function __acpi_os_unmap_table() will now call clear_fixmap().

Reported-by: Wei Xu <xuwei5@hisilicon.com>
Signed-off-by: Julien Grall <jgrall@amazon.com>

---

The discussion on the original thread [1] suggested to also zap it on
x86. This is technically not necessary today, so it is left alone for
now.

I looked at making the fixmap code common but the index are inverted
between Arm and x86.

[1] https://lore.kernel.org/xen-devel/5E26C935.9080107@hisilicon.com/
---
 xen/arch/arm/acpi/lib.c | 75 +++++++++++++++++++++++++++++++----------
 1 file changed, 58 insertions(+), 17 deletions(-)

diff --git a/xen/arch/arm/acpi/lib.c b/xen/arch/arm/acpi/lib.c
index 2192a5519171..eebaca695562 100644
--- a/xen/arch/arm/acpi/lib.c
+++ b/xen/arch/arm/acpi/lib.c
@@ -25,38 +25,79 @@
 #include <xen/init.h>
 #include <xen/mm.h>
 
+static bool fixmap_inuse;
+
 char *__acpi_map_table(paddr_t phys, unsigned long size)
 {
-    unsigned long base, offset, mapped_size;
-    int idx;
+    unsigned long base, offset;
+    mfn_t mfn;
+    unsigned int idx;
 
     /* No arch specific implementation after early boot */
     if ( system_state >= SYS_STATE_boot )
         return NULL;
 
     offset = phys & (PAGE_SIZE - 1);
-    mapped_size = PAGE_SIZE - offset;
-    set_fixmap(FIXMAP_ACPI_BEGIN, maddr_to_mfn(phys), PAGE_HYPERVISOR);
-    base = FIXMAP_ADDR(FIXMAP_ACPI_BEGIN);
+    base = FIXMAP_ADDR(FIXMAP_ACPI_BEGIN) + offset;
+
+    /* Check the fixmap is big enough to map the region */
+    if ( (FIXMAP_ADDR(FIXMAP_ACPI_END) + PAGE_SIZE - base) < size )
+        return NULL;
+
+    /* With the fixmap, we can only map one region at the time */
+    if ( fixmap_inuse )
+        return NULL;
 
-    /* Most cases can be covered by the below. */
+    fixmap_inuse = true;
+
+    size += offset;
+    mfn = maddr_to_mfn(phys);
     idx = FIXMAP_ACPI_BEGIN;
-    while ( mapped_size < size )
-    {
-        if ( ++idx > FIXMAP_ACPI_END )
-            return NULL;    /* cannot handle this */
-        phys += PAGE_SIZE;
-        set_fixmap(idx, maddr_to_mfn(phys), PAGE_HYPERVISOR);
-        mapped_size += PAGE_SIZE;
-    }
 
-    return ((char *) base + offset);
+    do {
+        set_fixmap(idx, mfn, PAGE_HYPERVISOR);
+        size -= min(size, (unsigned long)PAGE_SIZE);
+        mfn = mfn_add(mfn, 1);
+        idx++;
+    } while ( size > 0 );
+
+    return (char *)base;
 }
 
 bool __acpi_unmap_table(void *ptr, unsigned long size)
 {
-    return ( vaddr >= FIXMAP_ADDR(FIXMAP_ACPI_BEGIN) &&
-             vaddr < (FIXMAP_ADDR(FIXMAP_ACPI_END) + PAGE_SIZE) );
+    vaddr_t vaddr = (vaddr_t)ptr;
+    unsigned int idx;
+
+    /* We are only handling fixmap address in the arch code */
+    if ( vaddr < FIXMAP_ADDR(FIXMAP_ACPI_BEGIN) ||
+         vaddr >= FIXMAP_ADDR(FIXMAP_ACPI_END) )
+        return false;
+
+    /*
+     * __acpi_map_table() will always return a pointer in the first page
+     * for the ACPI fixmap region. The caller is expected to free with
+     * the same address.
+     */
+    ASSERT((vaddr & PAGE_MASK) == FIXMAP_ADDR(FIXMAP_ACPI_BEGIN));
+
+    /* The region allocated fit in the ACPI fixmap region. */
+    ASSERT(size < (FIXMAP_ADDR(FIXMAP_ACPI_END) + PAGE_SIZE - vaddr));
+    ASSERT(fixmap_inuse);
+
+    fixmap_inuse = false;
+
+    size += FIXMAP_ADDR(FIXMAP_ACPI_BEGIN) - vaddr;
+    idx = FIXMAP_ACPI_BEGIN;
+
+    do
+    {
+        clear_fixmap(idx);
+        size -= min(size, (unsigned long)PAGE_SIZE);
+        idx++;
+    } while ( size > 0 );
+
+    return true;
 }
 
 /* True to indicate PSCI 0.2+ is implemented */
-- 
2.17.1



  parent reply index

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-26 20:55 [PATCH 0/4] xen/arm: Unbreak ACPI Julien Grall
2020-09-26 20:55 ` [PATCH 1/4] xen/acpi: Rework acpi_os_map_memory() and acpi_os_unmap_memory() Julien Grall
2020-09-28  8:18   ` Jan Beulich
2020-09-28  9:58     ` Julien Grall
2020-09-28 10:09       ` Jan Beulich
2020-09-28 10:39         ` Julien Grall
2020-10-10  9:49           ` Julien Grall
2020-10-10 10:04             ` Julien Grall
2020-09-29 11:10   ` Rahul Singh
2020-10-01  0:06   ` Stefano Stabellini
2020-10-01 15:09     ` Julien Grall
2020-09-26 20:55 ` Julien Grall [this message]
2020-09-29 11:13   ` [PATCH 2/4] xen/arm: acpi: The fixmap area should always be cleared during failure/unmap Rahul Singh
2020-10-01  0:30   ` Stefano Stabellini
2020-10-01 15:14     ` Julien Grall
2020-09-26 20:55 ` [PATCH 3/4] xen/arm: Check if the platform is not using ACPI before initializing Dom0less Julien Grall
2020-09-29 11:17   ` Rahul Singh
2020-09-30 23:26   ` Stefano Stabellini
2020-09-26 20:55 ` [PATCH 4/4] xen/arm: Introduce fw_unreserved_regions() and use it Julien Grall
2020-09-30 23:40   ` Stefano Stabellini
2020-10-01 15:34     ` Julien Grall
2020-09-27  1:47 ` [PATCH 0/4] xen/arm: Unbreak ACPI Elliott Mitchell
2020-09-29 15:28   ` Elliott Mitchell
2020-09-28  6:47 ` Masami Hiramatsu
2020-09-28 13:00   ` Masami Hiramatsu
2020-10-16 22:33     ` Xen-ARM EFI/ACPI problems (was: Re: [PATCH 0/4] xen/arm: Unbreak ACPI) Elliott Mitchell
2020-10-17  5:12       ` Elliott Mitchell
2020-10-08 18:39   ` [PATCH 0/4] xen/arm: Unbreak ACPI Elliott Mitchell
2020-10-09  9:39     ` Julien Grall
2020-10-09 14:22       ` Elliott Mitchell
2020-10-09 18:15         ` Julien Grall
2020-10-09 22:36           ` Elliott Mitchell
2020-10-09 21:49   ` Elliott Mitchell
2020-10-10 11:02   ` Julien Grall
2020-10-12 19:02     ` Stefano Stabellini
2020-10-12 21:34       ` Elliott Mitchell
2020-10-14  1:06         ` Stefano Stabellini
2020-10-14  1:37           ` Elliott Mitchell
2020-10-14 17:47             ` Julien Grall
2020-10-15 18:00               ` Stefano Stabellini
2020-10-14 17:44       ` Julien Grall
2020-09-29 11:10 ` Rahul Singh
2020-09-29 15:29 ` Alex Bennée
2020-09-29 17:07   ` Julien Grall
2020-09-29 21:11     ` Alex Bennée
2020-09-29 23:39       ` André Przywara
2020-09-30  8:51         ` Alex Bennée
2020-09-30 10:35         ` Julien Grall
2020-09-30  9:42       ` Julien Grall
2020-09-30 10:38         ` Alex Bennée
2020-09-30 11:10           ` Julien Grall

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200926205542.9261-3-julien@xen.org \
    --to=julien@xen.org \
    --cc=Volodymyr_Babchuk@epam.com \
    --cc=alex.bennee@linaro.org \
    --cc=andre.przywara@arm.com \
    --cc=bertrand.marquis@arm.com \
    --cc=ehem+xen@m5p.com \
    --cc=jgrall@amazon.com \
    --cc=masami.hiramatsu@linaro.org \
    --cc=sstabellini@kernel.org \
    --cc=xen-devel@lists.xenproject.org \
    --cc=xuwei5@hisilicon.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Xen-Devel Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/xen-devel/0 xen-devel/git/0.git
	git clone --mirror https://lore.kernel.org/xen-devel/1 xen-devel/git/1.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 xen-devel xen-devel/ https://lore.kernel.org/xen-devel \
		xen-devel@lists.xenproject.org xen-devel@lists.xen.org
	public-inbox-index xen-devel

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.xenproject.lists.xen-devel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git