Messages in this thread | | | Date | Sun, 7 Apr 2024 11:47:00 +0800 | Subject | Re: [PATCH v19 080/130] KVM: TDX: restore host xsave state when exit from the guest TD | From | Binbin Wu <> |
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On 2/26/2024 4:26 PM, isaku.yamahata@intel.com wrote: > From: Isaku Yamahata <isaku.yamahata@intel.com> > > On exiting from the guest TD, xsave state is clobbered. Restore xsave > state on TD exit. > > Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com> > --- > v19: > - Add EXPORT_SYMBOL_GPL(host_xcr0) > > v15 -> v16: > - Added CET flag mask > > Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com> > --- > arch/x86/kvm/vmx/tdx.c | 19 +++++++++++++++++++ > arch/x86/kvm/x86.c | 1 + > 2 files changed, 20 insertions(+) > > diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c > index 9616b1aab6ce..199226c6cf55 100644 > --- a/arch/x86/kvm/vmx/tdx.c > +++ b/arch/x86/kvm/vmx/tdx.c > @@ -2,6 +2,7 @@ > #include <linux/cpu.h> > #include <linux/mmu_context.h> > > +#include <asm/fpu/xcr.h> > #include <asm/tdx.h> > > #include "capabilities.h" > @@ -534,6 +535,23 @@ void tdx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) > */ > } > > +static void tdx_restore_host_xsave_state(struct kvm_vcpu *vcpu) > +{ > + struct kvm_tdx *kvm_tdx = to_kvm_tdx(vcpu->kvm); > + > + if (static_cpu_has(X86_FEATURE_XSAVE) && > + host_xcr0 != (kvm_tdx->xfam & kvm_caps.supported_xcr0)) > + xsetbv(XCR_XFEATURE_ENABLED_MASK, host_xcr0); > + if (static_cpu_has(X86_FEATURE_XSAVES) && > + /* PT can be exposed to TD guest regardless of KVM's XSS support */ The comment needs to be updated to reflect the case for CET.
> + host_xss != (kvm_tdx->xfam & > + (kvm_caps.supported_xss | XFEATURE_MASK_PT | TDX_TD_XFAM_CET)))
For TDX_TD_XFAM_CET, maybe no need to make it TDX specific?
BTW, the definitions for XFEATURE_MASK_CET_USER/XFEATURE_MASK_CET_KERNEL have been merged. https://lore.kernel.org/all/20230613001108.3040476-25-rick.p.edgecombe%40intel.com You can resolve the TODO in https://lore.kernel.org/kvm/5eca97e6a3978cf4dcf1cff21be6ec8b639a66b9.1708933498.git.isaku.yamahata@intel.com/
> + wrmsrl(MSR_IA32_XSS, host_xss); > + if (static_cpu_has(X86_FEATURE_PKU) && > + (kvm_tdx->xfam & XFEATURE_MASK_PKRU)) > + write_pkru(vcpu->arch.host_pkru); > +} > + > static noinstr void tdx_vcpu_enter_exit(struct vcpu_tdx *tdx) > { > struct tdx_module_args args; > @@ -609,6 +627,7 @@ fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu) > > tdx_vcpu_enter_exit(tdx); > > + tdx_restore_host_xsave_state(vcpu); > tdx->host_state_need_restore = true; > > vcpu->arch.regs_avail &= ~VMX_REGS_LAZY_LOAD_SET; > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 23ece956c816..b361d948140f 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -315,6 +315,7 @@ const struct kvm_stats_header kvm_vcpu_stats_header = { > }; > > u64 __read_mostly host_xcr0; > +EXPORT_SYMBOL_GPL(host_xcr0); > > static struct kmem_cache *x86_emulator_cache; >
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