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x86/tdx: Fix off-by-one in port I/O handling

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handle_in() and handle_out() in arch/x86/coco/tdx/tdx.c use:

    u64 mask = GENMASK(BITS_PER_BYTE * size, 0);

GENMASK(h, l) includes bit h. For size=1 (INB), this produces
GENMASK(8, 0) = 0x1FF (9 bits) instead of GENMASK(7, 0) = 0xFF (8
bits). The mask is one bit too wide for all I/O sizes.

Fix the mask calculation.

Fixes: 0314994883 ("x86/tdx: Port I/O: Add runtime hypercalls")
Reported-by: Borys Tsyrulnikov <tsyrulnikov.borys@gmail.com>
Signed-off-by: Kiryl Shutsemau (Meta) <kas@kernel.org>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Reviewed-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Link: https://lore.kernel.org/all/CAKw_Dz96rfSQc6Rn+9QBcUFHhmkK+9zu+P=bxowfZwxrATCBRg@mail.gmail.com/
Cc:stable@vger.kernel.org
Link: https://patch.msgid.link/20260713133753.223947-2-kirill@shutemov.name
This commit is contained in:
Kiryl Shutsemau (Meta) 2026-07-13 14:37:51 +01:00 committed by Dave Hansen
parent a13c140cc2
commit 0f63e656b1
1 changed files with 2 additions and 2 deletions
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4
arch/x86/coco/tdx/tdx.c
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@ -694,7 +694,7 @@ static bool handle_in(struct pt_regs *regs, int size, int port)
.r13 = PORT_READ,
.r14 = port,
};
u64 mask = GENMASK(BITS_PER_BYTE * size, 0);
u64 mask = GENMASK(BITS_PER_BYTE * size - 1, 0);
bool success;
/*
@ -714,7 +714,7 @@ static bool handle_in(struct pt_regs *regs, int size, int port)
static bool handle_out(struct pt_regs *regs, int size, int port)
{
u64 mask = GENMASK(BITS_PER_BYTE * size, 0);
u64 mask = GENMASK(BITS_PER_BYTE * size - 1, 0);
/*
* Emulate the I/O write via hypercall. More info about ABI can be found