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Message-ID: <20241021105723.2707507-3-kirill.shutemov@linux.intel.com>
Date: Mon, 21 Oct 2024 13:57:23 +0300
From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To: Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>,
x86@...nel.org,
"H. Peter Anvin" <hpa@...or.com>,
Andy Lutomirski <luto@...nel.org>
Cc: Albert Ou <aou@...s.berkeley.edu>,
Alexei Starovoitov <ast@...nel.org>,
Andrea Parri <parri.andrea@...il.com>,
Arnd Bergmann <arnd@...db.de>,
Daniel Borkmann <daniel@...earbox.net>,
Eric Chan <ericchancf@...gle.com>,
Jason Gunthorpe <jgg@...pe.ca>,
Kai Huang <kai.huang@...el.com>,
Kefeng Wang <wangkefeng.wang@...wei.com>,
Kent Overstreet <kent.overstreet@...ux.dev>,
Palmer Dabbelt <palmer@...osinc.com>,
Paul Walmsley <paul.walmsley@...ive.com>,
Russell King <linux@...linux.org.uk>,
Samuel Holland <samuel.holland@...ive.com>,
Suren Baghdasaryan <surenb@...gle.com>,
Yuntao Wang <ytcoode@...il.com>,
linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org,
linux-riscv@...ts.infradead.org,
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
Tom Lendacky <thomas.lendacky@....com>,
Ashish Kalra <ashish.kalra@....com>,
"Maciej W. Rozycki" <macro@...am.me.uk>
Subject: [PATCHv2 2/2] x86/mm: Make memremap(MEMREMAP_WB) map memory as encrypted by default
Currently memremap(MEMREMAP_WB) produces decrypted/shared mapping:
memremap(MEMREMAP_WB)
arch_memremap_wb()
ioremap_cache()
__ioremap_caller(.encrytped = false)
It is a bad default. On TDX guests, access via shared mapping can be
destructive[1].
Kernel already provides a way to request decrypted mapping explicitly
via MEMREMAP_DEC flag.
Make memremap(MEMREMAP_WB) produce encrypted/private mapping by default
unless MEMREMAP_DEC is specified.
It fixes crash on kexec in TDX guests if CONFIG_EISA is enabled.
[1] https://lore.kernel.org/all/20240822095122.736522-1-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Cc: Tom Lendacky <thomas.lendacky@....com>
Cc: Ashish Kalra <ashish.kalra@....com>
Cc: "Maciej W. Rozycki" <macro@...am.me.uk>
---
arch/x86/include/asm/io.h | 3 +++
arch/x86/mm/ioremap.c | 8 ++++++++
2 files changed, 11 insertions(+)
diff --git a/arch/x86/include/asm/io.h b/arch/x86/include/asm/io.h
index 1d60427379c9..1a3a34b40598 100644
--- a/arch/x86/include/asm/io.h
+++ b/arch/x86/include/asm/io.h
@@ -180,6 +180,9 @@ extern void __iomem *ioremap_prot(resource_size_t offset, unsigned long size, un
extern void __iomem *ioremap_encrypted(resource_size_t phys_addr, unsigned long size);
#define ioremap_encrypted ioremap_encrypted
+void *arch_memremap_wb(phys_addr_t phys_addr, size_t size, unsigned long flags);
+#define arch_memremap_wb arch_memremap_wb
+
/**
* ioremap - map bus memory into CPU space
* @offset: bus address of the memory
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 70b02fc61d93..f04df30f0a27 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -503,6 +503,14 @@ void iounmap(volatile void __iomem *addr)
}
EXPORT_SYMBOL(iounmap);
+void *arch_memremap_wb(phys_addr_t phys_addr, size_t size, unsigned long flags)
+{
+ if (flags & MEMREMAP_DEC)
+ return (void __force *)ioremap_cache(phys_addr, size);
+
+ return (void __force *)ioremap_encrypted(phys_addr, size);
+}
+
/*
* Convert a physical pointer to a virtual kernel pointer for /dev/mem
* access
--
2.45.2
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