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d="scan'208";a="43332330" From: Andrew Cooper To: Xen-devel CC: Andrew Cooper , Jan Beulich , =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= , Wei Liu Subject: [PATCH 1/5] x86/xstate: Elide redundant writes in set_xcr0() Date: Mon, 3 May 2021 16:39:34 +0100 Message-ID: <20210503153938.14109-2-andrew.cooper3@citrix.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20210503153938.14109-1-andrew.cooper3@citrix.com> References: <20210503153938.14109-1-andrew.cooper3@citrix.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @citrix.com) XSETBV is an expensive instruction as, amongst other things, it involves reconfiguring the instruction decode at the frontend of the pipeline. We have several paths which reconfigure %xcr0 in quick succession (the cont= ext switch path has 5, including the fpu save/restore helpers), and only a sing= le caller takes any care to try to skip redundant writes. Update set_xcr0() to perform amortisation automatically, and simplify the __context_switch() path as a consequence. Signed-off-by: Andrew Cooper Reviewed-by: Jan Beulich --- CC: Jan Beulich CC: Roger Pau Monn=C3=A9 CC: Wei Liu --- xen/arch/x86/domain.c | 4 +--- xen/arch/x86/xstate.c | 15 +++++++++++---- 2 files changed, 12 insertions(+), 7 deletions(-) diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c index 4dc27f798e..50a27197b5 100644 --- a/xen/arch/x86/domain.c +++ b/xen/arch/x86/domain.c @@ -1977,9 +1977,7 @@ static void __context_switch(void) memcpy(stack_regs, &n->arch.user_regs, CTXT_SWITCH_STACK_BYTES); if ( cpu_has_xsave ) { - u64 xcr0 =3D n->arch.xcr0 ?: XSTATE_FP_SSE; - - if ( xcr0 !=3D get_xcr0() && !set_xcr0(xcr0) ) + if ( !set_xcr0(n->arch.xcr0 ?: XSTATE_FP_SSE) ) BUG(); =20 if ( cpu_has_xsaves && is_hvm_vcpu(n) ) diff --git a/xen/arch/x86/xstate.c b/xen/arch/x86/xstate.c index 3794d9a5a5..f82dae8053 100644 --- a/xen/arch/x86/xstate.c +++ b/xen/arch/x86/xstate.c @@ -55,11 +55,18 @@ static inline bool xsetbv(u32 index, u64 xfeatures) return lo !=3D 0; } =20 -bool set_xcr0(u64 xfeatures) +bool set_xcr0(u64 val) { - if ( !xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures) ) - return false; 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d="scan'208";a="42942252" From: Andrew Cooper To: Xen-devel CC: Andrew Cooper , Jan Beulich , =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= , Wei Liu Subject: [PATCH 2/5] x86/xstate: Rename _xstate_ctxt_size() to hw_uncompressed_size() Date: Mon, 3 May 2021 16:39:35 +0100 Message-ID: <20210503153938.14109-3-andrew.cooper3@citrix.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20210503153938.14109-1-andrew.cooper3@citrix.com> References: <20210503153938.14109-1-andrew.cooper3@citrix.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @citrix.com) The latter is a more descriptive name, as it explicitly highlights the query from hardware. Simplify the internal logic using cpuid_count_ebx(), and drop the curr/max assertion as this property is guaranteed by the x86 ISA. Signed-off-by: Andrew Cooper Reviewed-by: Jan Beulich --- CC: Jan Beulich CC: Roger Pau Monn=C3=A9 CC: Wei Liu --- xen/arch/x86/xstate.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) diff --git a/xen/arch/x86/xstate.c b/xen/arch/x86/xstate.c index f82dae8053..e6c225a16b 100644 --- a/xen/arch/x86/xstate.c +++ b/xen/arch/x86/xstate.c @@ -554,19 +554,18 @@ void xstate_free_save_area(struct vcpu *v) v->arch.xsave_area =3D NULL; } =20 -static unsigned int _xstate_ctxt_size(u64 xcr0) +static unsigned int hw_uncompressed_size(uint64_t xcr0) { u64 act_xcr0 =3D get_xcr0(); - u32 eax, ebx =3D 0, ecx, edx; + unsigned int size; bool ok =3D set_xcr0(xcr0); =20 ASSERT(ok); - cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx); - ASSERT(ebx <=3D ecx); + size =3D cpuid_count_ebx(XSTATE_CPUID, 0); ok =3D set_xcr0(act_xcr0); ASSERT(ok); =20 - return ebx; + return size; } =20 /* Fastpath for common xstate size requests, avoiding reloads of xcr0. */ @@ -578,7 +577,7 @@ unsigned int xstate_ctxt_size(u64 xcr0) if ( xcr0 =3D=3D 0 ) return 0; =20 - return _xstate_ctxt_size(xcr0); + return hw_uncompressed_size(xcr0); } =20 /* Collect the information of processor's extended state */ @@ -635,14 +634,14 @@ void xstate_init(struct cpuinfo_x86 *c) * xsave_cntxt_size is the max size required by enabled features. * We know FP/SSE and YMM about eax, and nothing about edx at pres= ent. */ - xsave_cntxt_size =3D _xstate_ctxt_size(feature_mask); + xsave_cntxt_size =3D hw_uncompressed_size(feature_mask); printk("xstate: size: %#x and states: %#"PRIx64"\n", xsave_cntxt_size, xfeature_mask); } else { BUG_ON(xfeature_mask !=3D feature_mask); - BUG_ON(xsave_cntxt_size !=3D _xstate_ctxt_size(feature_mask)); + BUG_ON(xsave_cntxt_size !=3D hw_uncompressed_size(feature_mask)); } =20 if ( setup_xstate_features(bsp) && bsp ) --=20 2.11.0 From nobody Sat Nov 30 01:45:30 2024 Delivered-To: importer@patchew.org Received-SPF: pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) client-ip=192.237.175.120; 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Authentication-Results: esa2.hc3370-68.iphmx.com; dkim=none (message not signed) header.i=none IronPort-SDR: GmP/0IMBbxNpZqx3flufAKBbnNuepUNa6zZBqCJSu5LACseXfw6ekok5Z0rgXVko7KX9BIRgd3 mBvcUPI63l31kjEYczwPlFfJkZjevfhSbt7ca7YvmTuCzQMept3XJ4uupBCOIWMsEBIJcrYHEy L/KBJlZXSDmwHxjogGD3hRT4T/5Sc3m5NV3GGD/72f3orz9PTfpxBTAgPapVCWN/tocfcRQrnt 17bq54ACAzCZsff1MTMinMDTg+wHPOIGPe3KpdlWSOX/JHbWgqF0jdoPbANaDsIGZbWilv+/T9 NtY= X-SBRS: 5.1 X-MesageID: 42942253 X-Ironport-Server: esa2.hc3370-68.iphmx.com X-Remote-IP: 162.221.158.21 X-Policy: $RELAYED IronPort-HdrOrdr: A9a23:EOUCG6/QoiV6zIOdCWNuk+BfI+orLtY04lQ7vn1ZYzY9SK2lvu qpm+kW0gKxtS0YX2sulcvFFK6LR37d8pAd2/hoAZ6JWg76tGy0aLxz9IeK+UyYJwTS/vNQvJ 0QEJRWJ8b3CTFB4vrSwA79KNo4xcnCzabAv5a7815IbSVHL55t9B14DAHzKDwReCBjCYAiHJ SRouprzgDQG0g/VciwCnkbU+WrnbSi//iKDSIuPBIp5BKDijml8tfBYn+l9ywTTi9VxvMa+X XF+jaJnZmLie2xyRPXygboj6h+pd2J8LV+Lf3JrsAULzn24zzYAbhcZw== X-IronPort-AV: E=Sophos;i="5.82,270,1613451600"; d="scan'208";a="42942253" From: Andrew Cooper To: Xen-devel CC: Andrew Cooper , Jan Beulich , =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= , Wei Liu Subject: [PATCH 3/5] x86/xstate: Rework xstate_ctxt_size() as xstate_uncompressed_size() Date: Mon, 3 May 2021 16:39:36 +0100 Message-ID: <20210503153938.14109-4-andrew.cooper3@citrix.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20210503153938.14109-1-andrew.cooper3@citrix.com> References: <20210503153938.14109-1-andrew.cooper3@citrix.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @citrix.com) We're soon going to need a compressed helper of the same form. The size of the uncompressed image is a strictly a property of the highest user state. This can be calculated trivially with xstate_offsets/sizes, and is much faster than a CPUID instruction in the first place, let alone the t= wo XCR0 writes surrounding it. Retain the cross-check with hardware in debug builds, but forgo it normal builds. In particular, this means that the migration paths don't need to m= ess with XCR0 just to sanity check the buffer size. Signed-off-by: Andrew Cooper --- CC: Jan Beulich CC: Roger Pau Monn=C3=A9 CC: Wei Liu --- xen/arch/x86/domctl.c | 2 +- xen/arch/x86/hvm/hvm.c | 2 +- xen/arch/x86/xstate.c | 40 +++++++++++++++++++++++++++++++--------- xen/include/asm-x86/xstate.h | 2 +- 4 files changed, 34 insertions(+), 12 deletions(-) diff --git a/xen/arch/x86/domctl.c b/xen/arch/x86/domctl.c index e440bd021e..8c3552410d 100644 --- a/xen/arch/x86/domctl.c +++ b/xen/arch/x86/domctl.c @@ -899,7 +899,7 @@ long arch_do_domctl( uint32_t offset =3D 0; =20 #define PV_XSAVE_HDR_SIZE (2 * sizeof(uint64_t)) -#define PV_XSAVE_SIZE(xcr0) (PV_XSAVE_HDR_SIZE + xstate_ctxt_size(xcr0)) +#define PV_XSAVE_SIZE(xcr0) (PV_XSAVE_HDR_SIZE + xstate_uncompressed_size(= xcr0)) =20 ret =3D -ESRCH; if ( (evc->vcpu >=3D d->max_vcpus) || diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c index 28beacc45b..e5fda6b387 100644 --- a/xen/arch/x86/hvm/hvm.c +++ b/xen/arch/x86/hvm/hvm.c @@ -1203,7 +1203,7 @@ HVM_REGISTER_SAVE_RESTORE(CPU, hvm_save_cpu_ctxt, hvm= _load_cpu_ctxt, 1, =20 #define HVM_CPU_XSAVE_SIZE(xcr0) (offsetof(struct hvm_hw_cpu_xsave, \ save_area) + \ - xstate_ctxt_size(xcr0)) + xstate_uncompressed_size(xcr0)) =20 static int hvm_save_cpu_xsave_states(struct vcpu *v, hvm_domain_context_t = *h) { diff --git a/xen/arch/x86/xstate.c b/xen/arch/x86/xstate.c index e6c225a16b..d4c01da574 100644 --- a/xen/arch/x86/xstate.c +++ b/xen/arch/x86/xstate.c @@ -184,7 +184,7 @@ void expand_xsave_states(struct vcpu *v, void *dest, un= signed int size) /* Check there is state to serialise (i.e. at least an XSAVE_HDR) */ BUG_ON(!v->arch.xcr0_accum); /* Check there is the correct room to decompress into. */ - BUG_ON(size !=3D xstate_ctxt_size(v->arch.xcr0_accum)); + BUG_ON(size !=3D xstate_uncompressed_size(v->arch.xcr0_accum)); =20 if ( !(xsave->xsave_hdr.xcomp_bv & XSTATE_COMPACTION_ENABLED) ) { @@ -246,7 +246,7 @@ void compress_xsave_states(struct vcpu *v, const void *= src, unsigned int size) u64 xstate_bv, valid; =20 BUG_ON(!v->arch.xcr0_accum); - BUG_ON(size !=3D xstate_ctxt_size(v->arch.xcr0_accum)); + BUG_ON(size !=3D xstate_uncompressed_size(v->arch.xcr0_accum)); ASSERT(!xsave_area_compressed(src)); =20 xstate_bv =3D ((const struct xsave_struct *)src)->xsave_hdr.xstate_bv; @@ -568,16 +568,38 @@ static unsigned int hw_uncompressed_size(uint64_t xcr= 0) return size; } =20 -/* Fastpath for common xstate size requests, avoiding reloads of xcr0. */ -unsigned int xstate_ctxt_size(u64 xcr0) +unsigned int xstate_uncompressed_size(uint64_t xcr0) { - if ( xcr0 =3D=3D xfeature_mask ) - return xsave_cntxt_size; + unsigned int size; + int idx =3D flsl(xcr0) - 1; =20 - if ( xcr0 =3D=3D 0 ) - return 0; + /* + * The maximum size of an uncompressed XSAVE area is determined by the + * highest user state, as the size and offset of each component is fix= ed. + */ + if ( idx >=3D 2 ) + { + ASSERT(xstate_offsets[idx] && xstate_sizes[idx]); + size =3D xstate_offsets[idx] + xstate_sizes[idx]; + } + else + size =3D XSTATE_AREA_MIN_SIZE; =20 - return hw_uncompressed_size(xcr0); + /* In debug builds, cross-check our calculation with hardware. */ + if ( IS_ENABLED(CONFIG_DEBUG) ) + { + unsigned int hwsize; + + xcr0 |=3D XSTATE_FP_SSE; + hwsize =3D hw_uncompressed_size(xcr0); + + if ( size !=3D hwsize ) + printk_once(XENLOG_ERR "%s(%#"PRIx64") size %#x !=3D hwsize %#= x\n", + __func__, xcr0, size, hwsize); + size =3D hwsize; + } + + return size; } =20 /* Collect the information of processor's extended state */ diff --git a/xen/include/asm-x86/xstate.h b/xen/include/asm-x86/xstate.h index 7ab0bdde89..02d6f171b8 100644 --- a/xen/include/asm-x86/xstate.h +++ b/xen/include/asm-x86/xstate.h @@ -107,7 +107,7 @@ void compress_xsave_states(struct vcpu *v, const void *= src, unsigned int size); void xstate_free_save_area(struct vcpu *v); int xstate_alloc_save_area(struct vcpu *v); void xstate_init(struct cpuinfo_x86 *c); -unsigned int xstate_ctxt_size(u64 xcr0); +unsigned int xstate_uncompressed_size(uint64_t xcr0); =20 static inline uint64_t xgetbv(unsigned int index) { --=20 2.11.0 From nobody Sat Nov 30 01:45:30 2024 Delivered-To: importer@patchew.org Received-SPF: pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) client-ip=192.237.175.120; envelope-from=xen-devel-bounces@lists.xenproject.org; helo=lists.xenproject.org; Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) smtp.mailfrom=xen-devel-bounces@lists.xenproject.org; dmarc=pass(p=reject dis=none) header.from=citrix.com ARC-Seal: i=1; a=rsa-sha256; t=1620056411; cv=none; d=zohomail.com; s=zohoarc; b=QR3AlAP41AGFDhDHltijbfjKhmerAEXayRNUsyg6PwH7Qbqip/5H79dNNrGKPAa0Xqz5FyeF3t2MkufAC/zcI5AFowQNxh33z98xWfm2tyv7GK42XNed0eGUHEd1C11EclvZW7J55A74W6PXpnpph7WZj7O9/yy/2DCuTlIdSOg= ARC-Message-Signature: i=1; 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d="scan'208";a="43332332" From: Andrew Cooper To: Xen-devel CC: Andrew Cooper , Jan Beulich , =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= , Wei Liu Subject: [PATCH 4/5] x86/cpuid: Simplify recalculate_xstate() Date: Mon, 3 May 2021 16:39:37 +0100 Message-ID: <20210503153938.14109-5-andrew.cooper3@citrix.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20210503153938.14109-1-andrew.cooper3@citrix.com> References: <20210503153938.14109-1-andrew.cooper3@citrix.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @citrix.com) Make use of the new xstate_uncompressed_size() helper rather than maintaini= ng the running calculation while accumulating feature components. The rest of the CPUID data can come direct from the raw cpuid policy. All per-component data forms an ABI through the behaviour of the X{SAVE,RSTOR}* instructions, and are constant. Use for_each_set_bit() rather than opencoding a slightly awkward version of it. Mask the attributes in ecx down based on the visible features. This isn't actually necessary for any components or attributes defined at the ti= me of writing (up to AMX), but is added out of an abundance of caution. Signed-off-by: Andrew Cooper --- CC: Jan Beulich CC: Roger Pau Monn=C3=A9 CC: Wei Liu Using min() in for_each_set_bit() leads to awful code generation, as it prohibits the optimiations for spotting that the bitmap is <=3D BITS_PER_LO= NG. As p->xstate is long enough already, use a BUILD_BUG_ON() instead. --- xen/arch/x86/cpuid.c | 52 +++++++++++++++++-------------------------------= ---- 1 file changed, 17 insertions(+), 35 deletions(-) diff --git a/xen/arch/x86/cpuid.c b/xen/arch/x86/cpuid.c index 752bf244ea..c7f8388e5d 100644 --- a/xen/arch/x86/cpuid.c +++ b/xen/arch/x86/cpuid.c @@ -154,8 +154,7 @@ static void sanitise_featureset(uint32_t *fs) static void recalculate_xstate(struct cpuid_policy *p) { uint64_t xstates =3D XSTATE_FP_SSE; - uint32_t xstate_size =3D XSTATE_AREA_MIN_SIZE; - unsigned int i, Da1 =3D p->xstate.Da1; + unsigned int i, ecx_bits =3D 0, Da1 =3D p->xstate.Da1; =20 /* * The Da1 leaf is the only piece of information preserved in the comm= on @@ -167,61 +166,44 @@ static void recalculate_xstate(struct cpuid_policy *p) return; =20 if ( p->basic.avx ) - { xstates |=3D X86_XCR0_YMM; - xstate_size =3D max(xstate_size, - xstate_offsets[X86_XCR0_YMM_POS] + - xstate_sizes[X86_XCR0_YMM_POS]); - } =20 if ( p->feat.mpx ) - { xstates |=3D X86_XCR0_BNDREGS | X86_XCR0_BNDCSR; - xstate_size =3D max(xstate_size, - xstate_offsets[X86_XCR0_BNDCSR_POS] + - xstate_sizes[X86_XCR0_BNDCSR_POS]); - } =20 if ( p->feat.avx512f ) - { xstates |=3D X86_XCR0_OPMASK | X86_XCR0_ZMM | X86_XCR0_HI_ZMM; - xstate_size =3D max(xstate_size, - xstate_offsets[X86_XCR0_HI_ZMM_POS] + - xstate_sizes[X86_XCR0_HI_ZMM_POS]); - } =20 if ( p->feat.pku ) - { xstates |=3D X86_XCR0_PKRU; - xstate_size =3D max(xstate_size, - xstate_offsets[X86_XCR0_PKRU_POS] + - xstate_sizes[X86_XCR0_PKRU_POS]); - } =20 - p->xstate.max_size =3D xstate_size; + /* Subleaf 0 */ + p->xstate.max_size =3D + xstate_uncompressed_size(xstates & ~XSTATE_XSAVES_ONLY); p->xstate.xcr0_low =3D xstates & ~XSTATE_XSAVES_ONLY; p->xstate.xcr0_high =3D (xstates & ~XSTATE_XSAVES_ONLY) >> 32; =20 + /* Subleaf 1 */ p->xstate.Da1 =3D Da1; if ( p->xstate.xsaves ) { + ecx_bits |=3D 3; /* Align64, XSS */ p->xstate.xss_low =3D xstates & XSTATE_XSAVES_ONLY; p->xstate.xss_high =3D (xstates & XSTATE_XSAVES_ONLY) >> 32; } - else - xstates &=3D ~XSTATE_XSAVES_ONLY; =20 - for ( i =3D 2; i < min(63ul, ARRAY_SIZE(p->xstate.comp)); ++i ) + /* Subleafs 2+ */ + xstates &=3D ~XSTATE_FP_SSE; + BUILD_BUG_ON(ARRAY_SIZE(p->xstate.comp) < 63); + for_each_set_bit ( i, &xstates, 63 ) { - uint64_t curr_xstate =3D 1ul << i; - - if ( !(xstates & curr_xstate) ) - continue; - - p->xstate.comp[i].size =3D xstate_sizes[i]; - p->xstate.comp[i].offset =3D xstate_offsets[i]; - p->xstate.comp[i].xss =3D curr_xstate & XSTATE_XSAVES_ONLY; - p->xstate.comp[i].align =3D curr_xstate & xstate_align; + /* + * Pass through size (eax) and offset (ebx) directly. Visbility of + * attributes in ecx limited by visible features in Da1. + */ + p->xstate.raw[i].a =3D raw_cpuid_policy.xstate.raw[i].a; + p->xstate.raw[i].b =3D raw_cpuid_policy.xstate.raw[i].b; + p->xstate.raw[i].c =3D raw_cpuid_policy.xstate.raw[i].c & ecx_bits; } } =20 --=20 2.11.0 From nobody Sat Nov 30 01:45:30 2024 Delivered-To: importer@patchew.org Received-SPF: pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) client-ip=192.237.175.120; envelope-from=xen-devel-bounces@lists.xenproject.org; helo=lists.xenproject.org; Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) smtp.mailfrom=xen-devel-bounces@lists.xenproject.org; dmarc=pass(p=reject dis=none) header.from=citrix.com ARC-Seal: i=1; a=rsa-sha256; t=1620056409; cv=none; d=zohomail.com; s=zohoarc; b=cg//Fq6ajqXfl2AGONM10lG07QM8m6zplg1sDrM7su+CDbBeXsD1sAGhbpx6bLIC2Dyr7OXwD7lUre+ZtOfGNRkWBJJVebXgFfeh5oBagG1mwZ+t6lPflLc/cPmeJOLsTOBTUBw/ZanjPBF5mI6O6XNsfniW1bAfZG4Nr/6HjPQ= ARC-Message-Signature: i=1; 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d="scan'208";a="43332334" From: Andrew Cooper To: Xen-devel CC: Andrew Cooper , Jan Beulich , =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= , Wei Liu Subject: [PATCH 5/5] x86/cpuid: Fix handling of xsave dynamic leaves Date: Mon, 3 May 2021 16:39:38 +0100 Message-ID: <20210503153938.14109-6-andrew.cooper3@citrix.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20210503153938.14109-1-andrew.cooper3@citrix.com> References: <20210503153938.14109-1-andrew.cooper3@citrix.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @citrix.com) If max leaf is greater than 0xd but xsave not available to the guest, then = the current XSAVE size should not be filled in. This is a latent bug for now as the guest max leaf is 0xd, but will become problematic in the future. The comment concerning XSS state is wrong. VT-x doesn't manage host/guest state automatically, but there is provision for "host only" bits to be set,= so the implications are still accurate. Introduce {xstate,hw}_compressed_size() helpers to mirror the uncompressed ones. Signed-off-by: Andrew Cooper Reviewed-by: Jan Beulich --- CC: Jan Beulich CC: Roger Pau Monn=C3=A9 CC: Wei Liu --- xen/arch/x86/cpuid.c | 23 +++++++-------------- xen/arch/x86/xstate.c | 49 ++++++++++++++++++++++++++++++++++++++++= ++++ xen/include/asm-x86/xstate.h | 1 + 3 files changed, 57 insertions(+), 16 deletions(-) diff --git a/xen/arch/x86/cpuid.c b/xen/arch/x86/cpuid.c index c7f8388e5d..92745aa63f 100644 --- a/xen/arch/x86/cpuid.c +++ b/xen/arch/x86/cpuid.c @@ -1041,24 +1041,15 @@ void guest_cpuid(const struct vcpu *v, uint32_t lea= f, case XSTATE_CPUID: switch ( subleaf ) { + case 0: + if ( p->basic.xsave ) + res->b =3D xstate_uncompressed_size(v->arch.xcr0); + break; + case 1: if ( p->xstate.xsaves ) - { - /* - * TODO: Figure out what to do for XSS state. VT-x manages - * host vs guest MSR_XSS automatically, so as soon as we s= tart - * supporting any XSS states, the wrong XSS will be in - * context. - */ - BUILD_BUG_ON(XSTATE_XSAVES_ONLY !=3D 0); - - /* - * Read CPUID[0xD,0/1].EBX from hardware. They vary with - * enabled XSTATE, and appropraite XCR0|XSS are in context. - */ - case 0: - res->b =3D cpuid_count_ebx(leaf, subleaf); - } + res->b =3D xstate_compressed_size(v->arch.xcr0 | + v->arch.msrs->xss.raw); break; } break; diff --git a/xen/arch/x86/xstate.c b/xen/arch/x86/xstate.c index d4c01da574..03489f0cf4 100644 --- a/xen/arch/x86/xstate.c +++ b/xen/arch/x86/xstate.c @@ -602,6 +602,55 @@ unsigned int xstate_uncompressed_size(uint64_t xcr0) return size; } =20 +static unsigned int hw_compressed_size(uint64_t xstates) +{ + uint64_t curr_xcr0 =3D get_xcr0(), curr_xss =3D get_msr_xss(); + unsigned int size; + bool ok; + + ok =3D set_xcr0(xstates & ~XSTATE_XSAVES_ONLY); + ASSERT(ok); + set_msr_xss(xstates & XSTATE_XSAVES_ONLY); + + size =3D cpuid_count_ebx(XSTATE_CPUID, 1); + + ok =3D set_xcr0(curr_xcr0); + ASSERT(ok); + set_msr_xss(curr_xss); + + return size; +} + +unsigned int xstate_compressed_size(uint64_t xstates) +{ + unsigned int i, size =3D XSTATE_AREA_MIN_SIZE; + + xstates &=3D ~XSTATE_FP_SSE; + for_each_set_bit ( i, &xstates, 63 ) + { + if ( test_bit(i, &xstate_align) ) + size =3D ROUNDUP(size, 64); + + size +=3D xstate_sizes[i]; + } + + /* In debug builds, cross-check our calculation with hardware. */ + if ( IS_ENABLED(CONFIG_DEBUG) ) + { + unsigned int hwsize; + + xstates |=3D XSTATE_FP_SSE; + hwsize =3D hw_compressed_size(xstates); + + if ( size !=3D hwsize ) + printk_once(XENLOG_ERR "%s(%#"PRIx64") size %#x !=3D hwsize %#= x\n", + __func__, xstates, size, hwsize); + size =3D hwsize; + } + + return size; +} + /* Collect the information of processor's extended state */ void xstate_init(struct cpuinfo_x86 *c) { diff --git a/xen/include/asm-x86/xstate.h b/xen/include/asm-x86/xstate.h index 02d6f171b8..ecf7bbc5cd 100644 --- a/xen/include/asm-x86/xstate.h +++ b/xen/include/asm-x86/xstate.h @@ -108,6 +108,7 @@ void xstate_free_save_area(struct vcpu *v); int xstate_alloc_save_area(struct vcpu *v); void xstate_init(struct cpuinfo_x86 *c); unsigned int xstate_uncompressed_size(uint64_t xcr0); +unsigned int xstate_compressed_size(uint64_t states); =20 static inline uint64_t xgetbv(unsigned int index) { --=20 2.11.0