x86/fpu/xstate: Fix last_good_offset in setup_xstate_features() (c12e13dc) · Commits · 戴 / test

The function setup_xstate_features() uses CPUID to find each xfeature's standard-format offset and size. Since XSAVES always uses the compacted format, supervisor xstates are *NEVER* in the standard-format and their offsets are left as -1's. However, they are still being tracked as last_good_offset. Fix it by tracking only user xstate offsets. [ bp: Use xfeature_is_supervisor() and save an indentation level. Drop now unused xfeature_is_user(). ] Signed-off-by:

Yu-cheng Yu <yu-cheng.yu@intel.com> Signed-off-by:

Borislav Petkov <bp@suse.de> Reviewed-by:

Dave Hansen <dave.hansen@linux.intel.com> Link: https://lkml.kernel.org/r/20200109211452.27369-2-yu-cheng.yu@intel.com

arch/x86/kernel/fpu/xstate.c

+13 −14

Original line number	Diff line number	Diff line
		@@ -120,11 +120,6 @@ static bool xfeature_is_supervisor(int xfeature_nr)
		return ecx & 1;
		}

		static bool xfeature_is_user(int xfeature_nr)
		{
		return !xfeature_is_supervisor(xfeature_nr);
		}

		/*
		* When executing XSAVEOPT (or other optimized XSAVE instructions), if
		* a processor implementation detects that an FPU state component is still
		@@ -265,21 +260,25 @@ static void __init setup_xstate_features(void)

		cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx);

		xstate_sizes[i] = eax;

		/*
		* If an xfeature is supervisor state, the offset
		* in EBX is invalid. We leave it to -1.
		* If an xfeature is supervisor state, the offset in EBX is
		* invalid, leave it to -1.
		*/
		if (xfeature_is_user(i))
		if (xfeature_is_supervisor(i))
		continue;

		xstate_offsets[i] = ebx;

		xstate_sizes[i] = eax;
		/*
		* In our xstate size checks, we assume that the
		* highest-numbered xstate feature has the
		* highest offset in the buffer. Ensure it does.
		* In our xstate size checks, we assume that the highest-numbered
		* xstate feature has the highest offset in the buffer. Ensure
		* it does.
		*/
		WARN_ONCE(last_good_offset > xstate_offsets[i],
		"x86/fpu: misordered xstate at %d\n", last_good_offset);

		last_good_offset = xstate_offsets[i];
		}
		}

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