Date: Fri, 3 Feb 2023 00:27:01 GMT From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: 9b16d1435123 - stable/13 - amd64: do not enable PKRU if user disabled saving PKRU register in xsave mask Message-ID: <202302030027.3130R1rx006194@gitrepo.freebsd.org>
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The branch stable/13 has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=9b16d143512368ac33988c6ae54e7939db2ed036 commit 9b16d143512368ac33988c6ae54e7939db2ed036 Author: Konstantin Belousov <kib@FreeBSD.org> AuthorDate: 2023-01-27 10:45:02 +0000 Commit: Konstantin Belousov <kib@FreeBSD.org> CommitDate: 2023-02-03 00:26:12 +0000 amd64: do not enable PKRU if user disabled saving PKRU register in xsave mask (cherry picked from commit 153643a5bc8ac3b1d47fc8e4de18d8c8a59817da) --- sys/amd64/amd64/fpu.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) diff --git a/sys/amd64/amd64/fpu.c b/sys/amd64/amd64/fpu.c index 8be69a347d63..f51c042bf8de 100644 --- a/sys/amd64/amd64/fpu.c +++ b/sys/amd64/amd64/fpu.c @@ -394,6 +394,7 @@ void fpuinit(void) { register_t saveintr; + uint64_t cr4; u_int mxcsr; u_short control; @@ -401,7 +402,22 @@ fpuinit(void) fpuinit_bsp1(); if (use_xsave) { - load_cr4(rcr4() | CR4_XSAVE); + cr4 = rcr4(); + + /* + * Revert enablement of PKRU if user disabled its + * saving on context switches by clearing the bit in + * the xsave mask. Also redundantly clear the bit in + * cpu_stdext_feature2 to prevent pmap from ever + * trying to set the page table bits. + */ + if ((cpu_stdext_feature2 & CPUID_STDEXT2_PKU) != 0 && + (xsave_mask & XFEATURE_ENABLED_PKRU) == 0) { + cr4 &= ~CR4_PKE; + cpu_stdext_feature2 &= ~CPUID_STDEXT2_PKU; + } + + load_cr4(cr4 | CR4_XSAVE); load_xcr(XCR0, xsave_mask); }
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