Messages in this thread | | | Date | Thu, 27 Jul 2023 15:48:26 +0300 | From | kirill.shutemov@linux ... | Subject | Re: [PATCH v3 01/12] x86/tdx: Zero out the missing RSI in TDX_HYPERCALL macro |
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On Wed, Jul 26, 2023 at 11:25:03PM +1200, Kai Huang wrote: > In the TDX_HYPERCALL asm, after the TDCALL instruction returns from the > untrusted VMM, the registers that the TDX guest shares to the VMM need > to be cleared to avoid speculative execution of VMM-provided values. > > RSI is specified in the bitmap of those registers, but it is missing > when zeroing out those registers in the current TDX_HYPERCALL. > > It was there when it was originally added in commit 752d13305c78 > ("x86/tdx: Expand __tdx_hypercall() to handle more arguments"), but was > later removed in commit 1e70c680375a ("x86/tdx: Do not corrupt > frame-pointer in __tdx_hypercall()"), which was correct because %rsi is > later restored in the "pop %rsi". However a later commit 7a3a401874be > ("x86/tdx: Drop flags from __tdx_hypercall()") removed that "pop %rsi" > but forgot to add the "xor %rsi, %rsi" back. > > Fix by adding it back. > > Fixes: 7a3a401874be ("x86/tdx: Drop flags from __tdx_hypercall()") > Signed-off-by: Kai Huang <kai.huang@intel.com> > Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
-- Kiryl Shutsemau / Kirill A. Shutemov
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