github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-05-25 07:33:19 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

KVM: x86: Initialize kvm_caps.supported_xss

Browse Source 
Set original kvm_caps.supported_xss to (host_xss & KVM_SUPPORTED_XSS) if
XSAVES is supported. host_xss contains the host supported xstate feature
bits for thread FPU context switch, KVM_SUPPORTED_XSS includes all KVM
enabled XSS feature bits, the resulting value represents the supervisor
xstates that are available to guest and are backed by host FPU framework
for swapping {guest,host} XSAVE-managed registers/MSRs.

[sean: relocate and enhance comment about PT / XSS[8] ]

Signed-off-by: Yang Weijiang <weijiang.yang@intel.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Chao Gao <chao.gao@intel.com>
Tested-by: Mathias Krause <minipli@grsecurity.net>
Tested-by: John Allen <john.allen@amd.com>
Tested-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Link: https://lore.kernel.org/r/20250919223258.1604852-9-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Yang Weijiang 2025-09-19 15:32:15 -07:00 committed by Sean Christopherson
parent 9622e116d0
commit 779ed05511
1 changed files with 15 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
arch/x86/kvm/x86.c
View File

@ -217,6 +217,14 @@ static struct kvm_user_return_msrs __percpu *user_return_msrs;
| XFEATURE_MASK_BNDCSR | XFEATURE_MASK_AVX512 \
| XFEATURE_MASK_PKRU | XFEATURE_MASK_XTILE)
/*
* Note, KVM supports exposing PT to the guest, but does not support context
* switching PT via XSTATE (KVM's PT virtualization relies on perf; swapping
* PT via guest XSTATE would clobber perf state), i.e. KVM doesn't support
* IA32_XSS[bit 8] (guests can/must use RDMSR/WRMSR to save/restore PT MSRs).
*/
#define KVM_SUPPORTED_XSS 0
bool __read_mostly allow_smaller_maxphyaddr = 0;
EXPORT_SYMBOL_GPL(allow_smaller_maxphyaddr);
@ -3986,11 +3994,7 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
case MSR_IA32_XSS:
if (!guest_cpuid_has(vcpu, X86_FEATURE_XSAVES))
return KVM_MSR_RET_UNSUPPORTED;
/*
* KVM supports exposing PT to the guest, but does not support
* IA32_XSS[bit 8]. Guests have to use RDMSR/WRMSR rather than
* XSAVES/XRSTORS to save/restore PT MSRs.
*/
if (data & ~vcpu->arch.guest_supported_xss)
return 1;
if (vcpu->arch.ia32_xss == data)
@ -9822,14 +9826,17 @@ int kvm_x86_vendor_init(struct kvm_x86_init_ops *ops)
kvm_host.xcr0 = xgetbv(XCR_XFEATURE_ENABLED_MASK);
kvm_caps.supported_xcr0 = kvm_host.xcr0 & KVM_SUPPORTED_XCR0;
}
if (boot_cpu_has(X86_FEATURE_XSAVES)) {
rdmsrq(MSR_IA32_XSS, kvm_host.xss);
kvm_caps.supported_xss = kvm_host.xss & KVM_SUPPORTED_XSS;
}
kvm_caps.supported_quirks = KVM_X86_VALID_QUIRKS;
kvm_caps.inapplicable_quirks = KVM_X86_CONDITIONAL_QUIRKS;
rdmsrq_safe(MSR_EFER, &kvm_host.efer);
if (boot_cpu_has(X86_FEATURE_XSAVES))
rdmsrq(MSR_IA32_XSS, kvm_host.xss);
kvm_init_pmu_capability(ops->pmu_ops);
if (boot_cpu_has(X86_FEATURE_ARCH_CAPABILITIES))