netdev - [PATCH v4 1/1] x86/ioremap: Fix page aligned size calculation in __ioremap

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Date:   Tue, 22 Nov 2022 09:40:42 -0800
From:   Michael Kelley <mikelley@...rosoft.com>
To:     hpa@...or.com, kys@...rosoft.com, haiyangz@...rosoft.com,
        wei.liu@...nel.org, decui@...rosoft.com, luto@...nel.org,
        peterz@...radead.org, davem@...emloft.net, edumazet@...gle.com,
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        robh@...nel.org, kw@...ux.com, bhelgaas@...gle.com, arnd@...db.de,
        hch@...radead.org, m.szyprowski@...sung.com, robin.murphy@....com,
        thomas.lendacky@....com, brijesh.singh@....com, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
        Tianyu.Lan@...rosoft.com, kirill.shutemov@...ux.intel.com,
        sathyanarayanan.kuppuswamy@...ux.intel.com, ak@...ux.intel.com,
        isaku.yamahata@...el.com, dan.j.williams@...el.com,
        jane.chu@...cle.com, seanjc@...gle.com, tony.luck@...el.com,
        x86@...nel.org, linux-kernel@...r.kernel.org,
        linux-hyperv@...r.kernel.org, netdev@...r.kernel.org,
        linux-pci@...r.kernel.org, linux-arch@...r.kernel.org,
        iommu@...ts.linux.dev
Cc:     mikelley@...rosoft.com
Subject: [PATCH v4 1/1] x86/ioremap: Fix page aligned size calculation in __ioremap_caller()

Current code re-calculates the size after aligning the starting and
ending physical addresses on a page boundary. But the re-calculation
also embeds the masking of high order bits that exceed the size of
the physical address space (via PHYSICAL_PAGE_MASK). If the masking
removes any high order bits, the size calculation results in a huge
value that is likely to immediately fail.

Fix this by re-calculating the page-aligned size first. Then mask any
high order bits using PHYSICAL_PAGE_MASK.

Fixes: ffa71f33a820 ("x86, ioremap: Fix incorrect physical address handling in PAE mode")
Acked-by: Dave Hansen <dave.hansen@...ux.intel.com>
Signed-off-by: Michael Kelley <mikelley@...rosoft.com>
---

This patch was previously Patch 1 of a larger series[1].  Breaking
it out separately per discussion with Dave Hansen and Boris Petkov.

[1] https://lore.kernel.org/linux-hyperv/1668624097-14884-1-git-send-email-mikelley@microsoft.com/

 arch/x86/mm/ioremap.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 78c5bc6..6453fba 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -217,9 +217,15 @@ static void __ioremap_check_mem(resource_size_t addr, unsigned long size,
 	 * Mappings have to be page-aligned
 	 */
 	offset = phys_addr & ~PAGE_MASK;
-	phys_addr &= PHYSICAL_PAGE_MASK;
+	phys_addr &= PAGE_MASK;
 	size = PAGE_ALIGN(last_addr+1) - phys_addr;
 
+	/*
+	 * Mask out any bits not part of the actual physical
+	 * address, like memory encryption bits.
+	 */
+	phys_addr &= PHYSICAL_PAGE_MASK;
+
 	retval = memtype_reserve(phys_addr, (u64)phys_addr + size,
 						pcm, &new_pcm);
 	if (retval) {
-- 
1.8.3.1