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From: Ard Biesheuvel <ardb@kernel.org>
To: linux-efi@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>
Cc: Ard Biesheuvel <ardb@kernel.org>,
	linux-kernel@vger.kernel.org,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Arvind Sankar <nivedita@alum.mit.edu>,
	Bhupesh Sharma <bhsharma@redhat.com>,
	Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
Subject: [PATCH 1/6] efi/memreserve: register reservations as 'reserved' in /proc/iomem
Date: Fri,  6 Dec 2019 16:55:37 +0000	[thread overview]
Message-ID: <20191206165542.31469-2-ardb@kernel.org> (raw)
In-Reply-To: <20191206165542.31469-1-ardb@kernel.org>

Memory regions that are reserved using efi_mem_reserve_persistent()
are recorded in a special EFI config table which survives kexec,
allowing the incoming kernel to honour them as well. However,
such reservations are not visible in /proc/iomem, and so the kexec
tools that load the incoming kernel and its initrd into memory may
overwrite these reserved regions before the incoming kernel has a
chance to reserve them from further use.

Address this problem by adding these reservations to /proc/iomem as
they are created. Note that reservations that are inherited from a
previous kernel are memblock_reserve()'d early on, so they are already
visible in /proc/iomem.

Tested-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
Tested-by: Bhupesh Sharma <bhsharma@redhat.com>
Reviewed-by: Bhupesh Sharma <bhsharma@redhat.com>
Cc: <stable@vger.kernel.org> # v5.4+
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 drivers/firmware/efi/efi.c | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index d101f072c8f8..b0961950d918 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -979,6 +979,24 @@ static int __init efi_memreserve_map_root(void)
 	return 0;
 }
 
+static int efi_mem_reserve_iomem(phys_addr_t addr, u64 size)
+{
+	struct resource *res, *parent;
+
+	res = kzalloc(sizeof(struct resource), GFP_ATOMIC);
+	if (!res)
+		return -ENOMEM;
+
+	res->name	= "reserved";
+	res->flags	= IORESOURCE_MEM;
+	res->start	= addr;
+	res->end	= addr + size - 1;
+
+	/* we expect a conflict with a 'System RAM' region */
+	parent = request_resource_conflict(&iomem_resource, res);
+	return parent ? request_resource(parent, res) : 0;
+}
+
 int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
 {
 	struct linux_efi_memreserve *rsv;
@@ -1003,7 +1021,7 @@ int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
 			rsv->entry[index].size = size;
 
 			memunmap(rsv);
-			return 0;
+			return efi_mem_reserve_iomem(addr, size);
 		}
 		memunmap(rsv);
 	}
@@ -1013,6 +1031,12 @@ int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
 	if (!rsv)
 		return -ENOMEM;
 
+	rc = efi_mem_reserve_iomem(__pa(rsv), SZ_4K);
+	if (rc) {
+		free_page((unsigned long)rsv);
+		return rc;
+	}
+
 	/*
 	 * The memremap() call above assumes that a linux_efi_memreserve entry
 	 * never crosses a page boundary, so let's ensure that this remains true
@@ -1029,7 +1053,7 @@ int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
 	efi_memreserve_root->next = __pa(rsv);
 	spin_unlock(&efi_mem_reserve_persistent_lock);
 
-	return 0;
+	return efi_mem_reserve_iomem(addr, size);
 }
 
 static int __init efi_memreserve_root_init(void)
-- 
2.17.1


  reply	other threads:[~2019-12-06 16:56 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-06 16:55 [GIT PULL 0/6] EFI fixes for v5.5 Ard Biesheuvel
2019-12-06 16:55 ` Ard Biesheuvel [this message]
2019-12-08 13:33   ` [tip: efi/urgent] efi/memreserve: Register reservations as 'reserved' in /proc/iomem tip-bot2 for Ard Biesheuvel
2019-12-06 16:55 ` [PATCH 2/6] efi/gop: Return EFI_NOT_FOUND if there are no usable GOPs Ard Biesheuvel
2019-12-08 13:33   ` [tip: efi/urgent] " tip-bot2 for Arvind Sankar
2019-12-06 16:55 ` [PATCH 3/6] efi/gop: Return EFI_SUCCESS if a usable GOP was found Ard Biesheuvel
2019-12-08 13:33   ` [tip: efi/urgent] " tip-bot2 for Arvind Sankar
2019-12-06 16:55 ` [PATCH 4/6] efi/gop: Fix memory leak from __gop_query32/64 Ard Biesheuvel
2019-12-08 13:33   ` [tip: efi/urgent] efi/gop: Fix memory leak in __gop_query32/64() tip-bot2 for Arvind Sankar
2019-12-06 16:55 ` [PATCH 5/6] efi: fix type of unload field in efi_loaded_image_t Ard Biesheuvel
2019-12-08 13:33   ` [tip: efi/urgent] efi: Fix efi_loaded_image_t::unload type tip-bot2 for Arvind Sankar
2019-12-06 16:55 ` [PATCH 6/6] efi/earlycon: Remap entire framebuffer after page initialization Ard Biesheuvel
2019-12-08 13:33   ` [tip: efi/urgent] " tip-bot2 for Andy Shevchenko
2019-12-09 19:12   ` [PATCH 6/6] " Arvind Sankar
2019-12-09 19:24     ` Ard Biesheuvel
2019-12-10 20:05       ` Arvind Sankar
2019-12-11 11:26         ` Ard Biesheuvel
2019-12-11 15:55           ` Arvind Sankar

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