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From: Yang Zhong <yang.zhong@intel.com>
To: x86@kernel.org, kvm@vger.kernel.org,
	linux-kernel@vger.kernel.org, tglx@linutronix.de,
	mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com,
	pbonzini@redhat.com
Cc: seanjc@google.com, jun.nakajima@intel.com, kevin.tian@intel.com,
	jing2.liu@linux.intel.com, jing2.liu@intel.com,
	yang.zhong@intel.com
Subject: [PATCH 18/19] kvm: x86: AMX XCR0 support for guest
Date: Tue,  7 Dec 2021 19:03:58 -0500	[thread overview]
Message-ID: <20211208000359.2853257-19-yang.zhong@intel.com> (raw)
In-Reply-To: <20211208000359.2853257-1-yang.zhong@intel.com>

From: Jing Liu <jing2.liu@intel.com>

Two XCR0 bits are defined for AMX to support XSAVE mechanism. Bit 17 is
for tilecfg and bit 18 is for tiledata.

The value of XCR0[17:18] is always either 00b or 11b. Also, SDM recommends
that only 64-bit operating systems enable Intel AMX by setting
XCR0[18:17].

Signed-off-by: Jing Liu <jing2.liu@intel.com>
Signed-off-by: Yang Zhong <yang.zhong@intel.com>
---
 arch/x86/kvm/x86.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d212f6d2d39a..a9a608c8fa50 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -210,7 +210,7 @@ static struct kvm_user_return_msrs __percpu *user_return_msrs;
 #define KVM_SUPPORTED_XCR0     (XFEATURE_MASK_FP | XFEATURE_MASK_SSE \
 				| XFEATURE_MASK_YMM | XFEATURE_MASK_BNDREGS \
 				| XFEATURE_MASK_BNDCSR | XFEATURE_MASK_AVX512 \
-				| XFEATURE_MASK_PKRU)
+				| XFEATURE_MASK_PKRU | XFEATURE_MASK_XTILE)
 
 u64 __read_mostly host_efer;
 EXPORT_SYMBOL_GPL(host_efer);
@@ -1017,6 +1017,23 @@ static int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
 		if ((xcr0 & XFEATURE_MASK_AVX512) != XFEATURE_MASK_AVX512)
 			return 1;
 	}
+
+#ifdef CONFIG_X86_64
+	if ((xcr0 & XFEATURE_MASK_XTILE) &&
+	    ((xcr0 & XFEATURE_MASK_XTILE) != XFEATURE_MASK_XTILE))
+		return 1;
+#else
+	/*
+	 * Intel AMX instructions can be executed only in 64-bit mode but
+	 * XSAVE can operate on XTILECFG and XTILEDATA in any mode.
+	 * Since the FPU core follows SDM recommendation to set
+	 * XCR[18:17] only in 64-bit environment, here also prevent any
+	 * guest OS from setting the two bits when host is 32-bit.
+	 *
+	 * XFEATURE_MASK_XTILE cannot be used since it is 0 in this case.
+	 */
+	xcr0 &= ~(XFEATURE_MASK_XTILE_DATA | XFEATURE_MASK_XTILE_CFG);
+#endif
 	vcpu->arch.xcr0 = xcr0;
 
 	if ((xcr0 ^ old_xcr0) & XFEATURE_MASK_EXTEND)

  parent reply	other threads:[~2021-12-07 15:10 UTC|newest]

Thread overview: 80+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-08  0:03 [PATCH 00/19] AMX Support in KVM Yang Zhong
2021-12-08  0:03 ` [PATCH 01/19] x86/fpu: Extend prctl() with guest permissions Yang Zhong
2021-12-14  0:16   ` Thomas Gleixner
2021-12-08  0:03 ` [PATCH 02/19] x86/fpu: Prepare KVM for dynamically enabled states Yang Zhong
2021-12-13  9:12   ` Paolo Bonzini
2021-12-13 12:00     ` Thomas Gleixner
2021-12-13 12:45       ` Paolo Bonzini
2021-12-13 19:50         ` Thomas Gleixner
2021-12-08  0:03 ` [PATCH 03/19] kvm: x86: Fix xstate_required_size() to follow XSTATE alignment rule Yang Zhong
2021-12-08  0:03 ` [PATCH 04/19] kvm: x86: Check guest xstate permissions when KVM_SET_CPUID2 Yang Zhong
2021-12-08  0:03 ` [PATCH 05/19] x86/fpu: Move xfd initialization out of __fpstate_reset() to the callers Yang Zhong
2021-12-10 22:33   ` Thomas Gleixner
2021-12-08  0:03 ` [PATCH 06/19] x86/fpu: Add reallocation mechanims for KVM Yang Zhong
2021-12-08  0:03 ` [PATCH 07/19] kvm: x86: Propagate fpstate reallocation error to userspace Yang Zhong
2021-12-10 15:44   ` Paolo Bonzini
2021-12-08  0:03 ` [PATCH 08/19] x86/fpu: Move xfd_update_state() to xstate.c and export symbol Yang Zhong
2021-12-10 22:44   ` Thomas Gleixner
2021-12-08  0:03 ` [PATCH 09/19] kvm: x86: Prepare reallocation check Yang Zhong
2021-12-13  9:16   ` Paolo Bonzini
2021-12-14  7:06     ` Tian, Kevin
2021-12-14 10:16       ` Paolo Bonzini
2021-12-14 14:41         ` Liu, Jing2
2021-12-15  7:09           ` Tian, Kevin
2021-12-08  0:03 ` [PATCH 10/19] kvm: x86: Emulate WRMSR of guest IA32_XFD Yang Zhong
2021-12-10 16:02   ` Paolo Bonzini
2021-12-13  7:51     ` Liu, Jing2
2021-12-13  9:01       ` Paolo Bonzini
2021-12-14 10:26     ` Yang Zhong
2021-12-14 11:24       ` Paolo Bonzini
2021-12-10 23:09   ` Thomas Gleixner
2021-12-13 15:06   ` Paolo Bonzini
2021-12-13 19:45     ` Thomas Gleixner
2021-12-13 21:23       ` Thomas Gleixner
2021-12-14  7:16         ` Tian, Kevin
2021-12-08  0:03 ` [PATCH 11/19] kvm: x86: Check fpstate reallocation in XSETBV emulation Yang Zhong
2021-12-08  0:03 ` [PATCH 12/19] x86/fpu: Prepare KVM for bringing XFD state back in-sync Yang Zhong
2021-12-10 23:11   ` Thomas Gleixner
2021-12-08  0:03 ` [PATCH 13/19] kvm: x86: Disable WRMSR interception for IA32_XFD on demand Yang Zhong
2021-12-08  7:23   ` Liu, Jing2
2021-12-08  0:03 ` [PATCH 14/19] x86/fpu: Prepare for KVM XFD_ERR handling Yang Zhong
2021-12-10 16:16   ` Paolo Bonzini
2021-12-10 23:20   ` Thomas Gleixner
2021-12-08  0:03 ` [PATCH 15/19] kvm: x86: Save and restore guest XFD_ERR properly Yang Zhong
2021-12-10 16:23   ` Paolo Bonzini
2021-12-10 22:01   ` Paolo Bonzini
2021-12-12 13:10     ` Yang Zhong
2021-12-11  0:10   ` Thomas Gleixner
2021-12-11  1:31     ` Paolo Bonzini
2021-12-11  3:23       ` Tian, Kevin
2021-12-11 13:10       ` Thomas Gleixner
2021-12-11  3:07     ` Tian, Kevin
2021-12-11 13:29       ` Thomas Gleixner
2021-12-12  1:50         ` Tian, Kevin
2021-12-12  9:10           ` Paolo Bonzini
2021-12-08  0:03 ` [PATCH 16/19] kvm: x86: Introduce KVM_{G|S}ET_XSAVE2 ioctl Yang Zhong
2021-12-10 16:25   ` Paolo Bonzini
2021-12-10 16:30   ` Paolo Bonzini
2021-12-10 22:13     ` Paolo Bonzini
2021-12-13  8:23       ` Wang, Wei W
2021-12-13  9:24         ` Paolo Bonzini
2021-12-14  6:06           ` Wang, Wei W
2021-12-14  6:18             ` Paolo Bonzini
2021-12-15  2:39               ` Wang, Wei W
2021-12-15 13:42                 ` Paolo Bonzini
2021-12-16  8:25                   ` Wang, Wei W
2021-12-16 10:28                     ` Paolo Bonzini
2021-12-20 17:54       ` State Component 18 and Palette 1 (Re: [PATCH 16/19] kvm: x86: Introduce KVM_{G|S}ET_XSAVE2 ioctl) Nakajima, Jun
2021-12-22 14:44         ` Paolo Bonzini
2021-12-22 23:47           ` Nakajima, Jun
2021-12-22 14:52         ` Dave Hansen
2021-12-22 23:51           ` Nakajima, Jun
2021-12-13 10:10     ` [PATCH 16/19] kvm: x86: Introduce KVM_{G|S}ET_XSAVE2 ioctl Thomas Gleixner
2021-12-13 10:43       ` Paolo Bonzini
2021-12-13 12:40         ` Thomas Gleixner
2021-12-08  0:03 ` [PATCH 17/19] docs: virt: api.rst: Document the new KVM_{G, S}ET_XSAVE2 ioctls Yang Zhong
2021-12-08  0:03 ` Yang Zhong [this message]
2021-12-10 16:30   ` [PATCH 18/19] kvm: x86: AMX XCR0 support for guest Paolo Bonzini
2021-12-08  0:03 ` [PATCH 19/19] kvm: x86: Add AMX CPUIDs support Yang Zhong
2021-12-10 21:52   ` Paolo Bonzini
2021-12-11 21:20 ` [PATCH 00/19] AMX Support in KVM Thomas Gleixner

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