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a="68053896" X-IronPort-AV: E=Sophos;i="6.19,313,1754982000"; d="scan'208";a="68053896" X-CSE-ConnectionGUID: 2j+ZZLwKShGHa6BNPVxORA== X-CSE-MsgGUID: qs9qdH5nQLGfGnDJ/i30Rg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.19,313,1754982000"; d="scan'208";a="221537320" From: Zhao Liu To: Paolo Bonzini , Marcelo Tosatti Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org, Chao Gao , Xin Li , John Allen , Babu Moger , Mathias Krause , Dapeng Mi , Zide Chen , Xiaoyao Li , Chenyi Qiang , Farrah Chen , Zhao Liu , Yang Weijiang Subject: [PATCH v4 16/23] i386/kvm: Add save/restore support for KVM_REG_GUEST_SSP Date: Tue, 18 Nov 2025 11:42:24 +0800 Message-Id: <20251118034231.704240-17-zhao1.liu@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20251118034231.704240-1-zhao1.liu@intel.com> References: <20251118034231.704240-1-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=192.198.163.13; 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_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_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: 1763436249288158500 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 & restore 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 Reviewed-by: Xiaoyao Li 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 | 3 ++- target/i386/kvm/kvm.c | 39 +++++++++++++++++++++++++++++++++++++++ 2 files changed, 41 insertions(+), 1 deletion(-) diff --git a/target/i386/cpu.h b/target/i386/cpu.h index 661b798da4d0..c4412012c780 100644 --- a/target/i386/cpu.h +++ b/target/i386/cpu.h @@ -1982,7 +1982,7 @@ typedef struct CPUArchState { uint64_t fred_config; #endif =20 - /* CET MSRs */ + /* CET MSRs and register */ uint64_t u_cet; uint64_t s_cet; uint64_t pl0_ssp; /* also used for FRED */ @@ -1992,6 +1992,7 @@ typedef struct CPUArchState { #ifdef TARGET_X86_64 uint64_t int_ssp_table; #endif + uint64_t guest_ssp; =20 uint64_t tsc_adjust; uint64_t tsc_deadline; diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c index 4eb58ca19d79..1ebe20f7fb57 100644 --- a/target/i386/kvm/kvm.c +++ b/target/i386/kvm/kvm.c @@ -4292,6 +4292,35 @@ 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) { @@ -5445,6 +5474,11 @@ 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"); @@ -5517,6 +5551,11 @@ 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