linux-kernel - [PATCH 22/26] KVM: x86: Handle XSAVES CPUID adjustment in VMX code

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20200129234640.8147-23-sean.j.christopherson@intel.com>
Date:   Wed, 29 Jan 2020 15:46:36 -0800
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 22/26] KVM: x86: Handle XSAVES CPUID adjustment in VMX code

Move the clearing of the XSAVES CPUID bit into VMX, which has a separate
VMCS control to enable XSAVES in non-root, to to eliminate an instance of
the undesirable "unsigned f_* = *_supported ? F(*) : 0" pattern in the
common CPUID handling code.  Add a call to ->set_supported_cpuid() in
the leaf 0xD handling so that vendor code can update feature bits in the
index=1 sub-leaf (which contains the XSAVES bit) and teach
{svm,vmx}_set_supported_cpuid() how to handle non-zero indices.

Drop ->xsaves_supported() since CPUID adjustment was the only user.

No functional change intended.

Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
---
 arch/x86/include/asm/kvm_host.h | 1 -
 arch/x86/kvm/cpuid.c            | 6 ++++--
 arch/x86/kvm/svm.c              | 9 +++------
 arch/x86/kvm/vmx/vmx.c          | 9 ++++++++-
 4 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 3cd11257257c..ea076debe6f8 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1163,7 +1163,6 @@ struct kvm_x86_ops {
 	void (*handle_exit_irqoff)(struct kvm_vcpu *vcpu,
 		enum exit_fastpath_completion *exit_fastpath);
 
-	bool (*xsaves_supported)(void);
 	bool (*umip_emulated)(void);
 	bool (*pt_supported)(void);
 
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index ce7f6dfcf832..75971c254b4d 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -410,7 +410,6 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
 	unsigned f_gbpages = 0;
 	unsigned f_lm = 0;
 #endif
-	unsigned f_xsaves = kvm_x86_ops->xsaves_supported() ? F(XSAVES) : 0;
 	unsigned f_intel_pt = kvm_x86_ops->pt_supported() ? F(INTEL_PT) : 0;
 
 	/* cpuid 1.edx */
@@ -467,7 +466,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
 
 	/* cpuid 0xD.1.eax */
 	const u32 kvm_cpuid_D_1_eax_x86_features =
-		F(XSAVEOPT) | F(XSAVEC) | F(XGETBV1) | f_xsaves;
+		F(XSAVEOPT) | F(XSAVEC) | F(XGETBV1) | F(XSAVES);
 
 	/* all calls to cpuid_count() should be made on the same cpu */
 	get_cpu();
@@ -629,6 +628,9 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
 				entry[i].eax &= kvm_cpuid_D_1_eax_x86_features;
 				cpuid_mask(&entry[i].eax, CPUID_D_1_EAX);
 				entry[i].ebx = 0;
+
+				kvm_x86_ops->set_supported_cpuid(&entry[i]);
+
 				if (entry[i].eax & (F(XSAVES)|F(XSAVEC)))
 					entry[i].ebx =
 						xstate_required_size(supported,
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 2adc3a474b80..7d6f46399e5a 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -6054,6 +6054,9 @@ static void svm_cpuid_update(struct kvm_vcpu *vcpu)
 
 static void svm_set_supported_cpuid(struct kvm_cpuid_entry2 *entry)
 {
+	if (entry->index)
+		return;
+
 	switch (entry->function) {
 	case 0x1:
 		if (avic)
@@ -6096,11 +6099,6 @@ static int svm_get_lpage_level(void)
 	return PT_PDPE_LEVEL;
 }
 
-static bool svm_xsaves_supported(void)
-{
-	return boot_cpu_has(X86_FEATURE_XSAVES);
-}
-
 static bool svm_umip_emulated(void)
 {
 	return false;
@@ -7471,7 +7469,6 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = {
 
 	.cpuid_update = svm_cpuid_update,
 
-	.xsaves_supported = svm_xsaves_supported,
 	.umip_emulated = svm_umip_emulated,
 	.pt_supported = svm_pt_supported,
 
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index f244b2356847..941ac7296735 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7131,6 +7131,14 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
 
 static void vmx_set_supported_cpuid(struct kvm_cpuid_entry2 *entry)
 {
+	if (entry->index) {
+		if (WARN_ON_ONCE(entry->function != 0xd || entry->index != 1))
+			return;
+		if (!vmx_xsaves_supported())
+			cpuid_entry_clear(entry, X86_FEATURE_XSAVES);
+		return;
+	}
+
 	switch (entry->function) {
 	case 0x1:
 		if (nested)
@@ -7899,7 +7907,6 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = {
 
 	.check_intercept = vmx_check_intercept,
 	.handle_exit_irqoff = vmx_handle_exit_irqoff,
-	.xsaves_supported = vmx_xsaves_supported,
 	.umip_emulated = vmx_umip_emulated,
 	.pt_supported = vmx_pt_supported,
 
-- 
2.24.1