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a="63170919" X-IronPort-AV: E=Sophos;i="6.19,251,1754982000"; d="scan'208";a="63170919" X-CSE-ConnectionGUID: jD+M9+PjSPOEKLdIgJOBeA== X-CSE-MsgGUID: KF/E+hlwSPGCQTCB+6H/cA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.19,251,1754982000"; d="scan'208";a="184276104" From: Zhao Liu To: Paolo Bonzini , Marcelo Tosatti Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org, Chao Gao , John Allen , Babu Moger , Mathias Krause , Dapeng Mi , Zide Chen , Chenyi Qiang , Xiaoyao Li , Farrah Chen , Zhao Liu , Yang Weijiang Subject: [PATCH v3 14/20] i386/kvm: Add save/load support for KVM_REG_GUEST_SSP Date: Fri, 24 Oct 2025 14:56:26 +0800 Message-Id: <20251024065632.1448606-15-zhao1.liu@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20251024065632.1448606-1-zhao1.liu@intel.com> References: <20251024065632.1448606-1-zhao1.liu@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=198.175.65.20; envelope-from=zhao1.liu@intel.com; helo=mgamail.intel.com X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @intel.com) X-ZM-MESSAGEID: 1761287829183158500 Content-Type: text/plain; charset="utf-8" From: Yang Weijiang CET provides a new architectural register, shadow stack pointer (SSP), which cannot be directly encoded as a source, destination or memory operand in instructions. But Intel VMCS & VMCB provide fields to save/load guest & host's ssp. It's necessary to save & load Guest's ssp before & after migration. To support this, KVM implements Guest's SSP as a special KVM internal register - KVM_REG_GUEST_SSP, and allows QEMU to save & load it via KVM_GET_ONE_REG/KVM_SET_ONE_REG. Cache KVM_REG_GUEST_SSP in X86CPUState. Tested-by: Farrah Chen Signed-off-by: Yang Weijiang Co-developed-by: Chao Gao Signed-off-by: Chao Gao Co-developed-by: Zhao Liu Signed-off-by: Zhao Liu --- target/i386/cpu.h | 1 + target/i386/kvm/kvm.c | 39 +++++++++++++++++++++++++++++++++++++++ 2 files changed, 40 insertions(+) diff --git a/target/i386/cpu.h b/target/i386/cpu.h index 4edb977575e2..ad4287822831 100644 --- a/target/i386/cpu.h +++ b/target/i386/cpu.h @@ -2105,6 +2105,7 @@ typedef struct CPUArchState { uint64_t pl2_ssp; uint64_t pl3_ssp; uint64_t int_ssp_table; + uint64_t guest_ssp; =20 /* Fields up to this point are cleared by a CPU reset */ struct {} end_reset_fields; diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c index 92c2fd6d6aee..412e99ba5b53 100644 --- a/target/i386/kvm/kvm.c +++ b/target/i386/kvm/kvm.c @@ -4280,6 +4280,35 @@ static int kvm_put_msrs(X86CPU *cpu, KvmPutState lev= el) return kvm_buf_set_msrs(cpu); } =20 +static int kvm_put_kvm_regs(X86CPU *cpu) +{ + CPUX86State *env =3D &cpu->env; + int ret; + + if ((env->features[FEAT_7_0_ECX] & CPUID_7_0_ECX_CET_SHSTK)) { + ret =3D kvm_set_one_reg(CPU(cpu), KVM_X86_REG_KVM(KVM_REG_GUEST_SS= P), + &env->guest_ssp); + if (ret) { + return ret; + } + } + return 0; +} + +static int kvm_get_kvm_regs(X86CPU *cpu) +{ + CPUX86State *env =3D &cpu->env; + int ret; + + if ((env->features[FEAT_7_0_ECX] & CPUID_7_0_ECX_CET_SHSTK)) { + ret =3D kvm_get_one_reg(CPU(cpu), KVM_X86_REG_KVM(KVM_REG_GUEST_SS= P), + &env->guest_ssp); + if (ret) { + return ret; + } + } + return 0; +} =20 static int kvm_get_xsave(X86CPU *cpu) { @@ -5425,6 +5454,11 @@ int kvm_arch_put_registers(CPUState *cpu, KvmPutStat= e level, Error **errp) error_setg_errno(errp, -ret, "Failed to set MSRs"); return ret; } + ret =3D kvm_put_kvm_regs(x86_cpu); + if (ret < 0) { + error_setg_errno(errp, -ret, "Failed to set KVM type registers"); + return ret; + } ret =3D kvm_put_vcpu_events(x86_cpu, level); if (ret < 0) { error_setg_errno(errp, -ret, "Failed to set vCPU events"); @@ -5497,6 +5531,11 @@ int kvm_arch_get_registers(CPUState *cs, Error **err= p) error_setg_errno(errp, -ret, "Failed to get MSRs"); goto out; } + ret =3D kvm_get_kvm_regs(cpu); + if (ret < 0) { + error_setg_errno(errp, -ret, "Failed to get KVM type registers"); + goto out; + } ret =3D kvm_get_apic(cpu); if (ret < 0) { error_setg_errno(errp, -ret, "Failed to get APIC"); --=20 2.34.1