On 1/23/2024 7:53 AM, isaku.yamahata@xxxxxxxxx wrote:
From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
On exiting from the guest TD, xsave state is clobbered. Restore xsave
state on TD exit.
Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
---
v15 -> v16:
- Added CET flag mask
---
arch/x86/kvm/vmx/tdx.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 903f4abb3543..fe818cfde9e7 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"
@@ -584,6 +585,23 @@ 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 */
+ host_xss != (kvm_tdx->xfam &
+ (kvm_caps.supported_xss | XFEATURE_MASK_PT | TDX_TD_XFAM_CET)))
+ 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);
+}
+
The export of host_xcr0 in patch 67 can be moved to this path.
u64 __read_mostly host_xcr0;
+EXPORT_SYMBOL_GPL(host_xcr0);
static noinstr void tdx_vcpu_enter_exit(struct vcpu_tdx *tdx)
{
struct tdx_module_args args;
@@ -659,6 +677,7 @@ 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;
