Messages in this thread | | | Date | Fri, 12 Apr 2024 17:28:12 +0200 | Subject | Re: [PATCH v3 06/14] x86/sev: Use the SVSM to create a vCPU when not in VMPL0 | From | "Gupta, Pankaj" <> |
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On 3/25/2024 11:26 PM, Tom Lendacky wrote: > Using the RMPADJUST instruction, the VSMA attribute can only be changed > at VMPL0. An SVSM will be present when running at VMPL1 or a lower > privilege level. > > When an SVSM is present, use the SVSM_CORE_CREATE_VCPU call or the > SVSM_CORE_DESTROY_VCPU call to perform VMSA attribute changes. Use the > VMPL level supplied by the SVSM within the VMSA and when starting the > AP. > > Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.com>
> --- > arch/x86/include/asm/sev.h | 2 ++ > arch/x86/kernel/sev.c | 60 +++++++++++++++++++++++++++++++++----- > 2 files changed, 54 insertions(+), 8 deletions(-) > > diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h > index 204f0a4857d6..d7be613b7372 100644 > --- a/arch/x86/include/asm/sev.h > +++ b/arch/x86/include/asm/sev.h > @@ -229,6 +229,8 @@ struct svsm_call { > #define SVSM_CORE_CALL(x) ((0ULL << 32) | (x)) > #define SVSM_CORE_REMAP_CA 0 > #define SVSM_CORE_PVALIDATE 1 > +#define SVSM_CORE_CREATE_VCPU 2 > +#define SVSM_CORE_DELETE_VCPU 3 > > #ifdef CONFIG_AMD_MEM_ENCRYPT > extern void __sev_es_ist_enter(struct pt_regs *regs); > diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c > index d3e182d69d65..ea8b43a0f01b 100644 > --- a/arch/x86/kernel/sev.c > +++ b/arch/x86/kernel/sev.c > @@ -1016,7 +1016,7 @@ void snp_accept_memory(phys_addr_t start, phys_addr_t end) > set_pages_state(vaddr, npages, SNP_PAGE_STATE_PRIVATE); > } > > -static int snp_set_vmsa(void *va, bool vmsa) > +static int base_snp_set_vmsa(void *va, bool vmsa) > { > u64 attrs; > > @@ -1034,6 +1034,40 @@ static int snp_set_vmsa(void *va, bool vmsa) > return rmpadjust((unsigned long)va, RMP_PG_SIZE_4K, attrs); > } > > +static int svsm_snp_set_vmsa(void *va, void *caa, int apic_id, bool vmsa) > +{ > + struct svsm_call call = {}; > + unsigned long flags; > + int ret; > + > + local_irq_save(flags); > + > + call.caa = this_cpu_read(svsm_caa); > + call.rcx = __pa(va); > + > + if (vmsa) { > + /* Protocol 0, Call ID 2 */ > + call.rax = SVSM_CORE_CALL(SVSM_CORE_CREATE_VCPU); > + call.rdx = __pa(caa); > + call.r8 = apic_id; > + } else { > + /* Protocol 0, Call ID 3 */ > + call.rax = SVSM_CORE_CALL(SVSM_CORE_DELETE_VCPU); > + } > + > + ret = svsm_protocol(&call); > + > + local_irq_restore(flags); > + > + return ret; > +} > + > +static int snp_set_vmsa(void *va, void *caa, int apic_id, bool vmsa) > +{ > + return vmpl ? svsm_snp_set_vmsa(va, caa, apic_id, vmsa) > + : base_snp_set_vmsa(va, vmsa); > +} > + > #define __ATTR_BASE (SVM_SELECTOR_P_MASK | SVM_SELECTOR_S_MASK) > #define INIT_CS_ATTRIBS (__ATTR_BASE | SVM_SELECTOR_READ_MASK | SVM_SELECTOR_CODE_MASK) > #define INIT_DS_ATTRIBS (__ATTR_BASE | SVM_SELECTOR_WRITE_MASK) > @@ -1065,11 +1099,11 @@ static void *snp_alloc_vmsa_page(void) > return page_address(p + 1); > } > > -static void snp_cleanup_vmsa(struct sev_es_save_area *vmsa) > +static void snp_cleanup_vmsa(struct sev_es_save_area *vmsa, int apic_id) > { > int err; > > - err = snp_set_vmsa(vmsa, false); > + err = snp_set_vmsa(vmsa, NULL, apic_id, false); > if (err) > pr_err("clear VMSA page failed (%u), leaking page\n", err); > else > @@ -1080,6 +1114,7 @@ static int wakeup_cpu_via_vmgexit(u32 apic_id, unsigned long start_ip) > { > struct sev_es_save_area *cur_vmsa, *vmsa; > struct ghcb_state state; > + struct svsm_ca *caa; > unsigned long flags; > struct ghcb *ghcb; > u8 sipi_vector; > @@ -1126,6 +1161,12 @@ static int wakeup_cpu_via_vmgexit(u32 apic_id, unsigned long start_ip) > if (!vmsa) > return -ENOMEM; > > + /* > + * If an SVSM is present, then the SVSM CAA per-CPU variable will > + * have a value, otherwise it will be NULL. > + */ > + caa = per_cpu(svsm_caa, cpu); > + > /* CR4 should maintain the MCE value */ > cr4 = native_read_cr4() & X86_CR4_MCE; > > @@ -1173,11 +1214,11 @@ static int wakeup_cpu_via_vmgexit(u32 apic_id, unsigned long start_ip) > * VMPL level > * SEV_FEATURES (matches the SEV STATUS MSR right shifted 2 bits) > */ > - vmsa->vmpl = 0; > + vmsa->vmpl = vmpl; > vmsa->sev_features = sev_status >> 2; > > /* Switch the page over to a VMSA page now that it is initialized */ > - ret = snp_set_vmsa(vmsa, true); > + ret = snp_set_vmsa(vmsa, caa, apic_id, true); > if (ret) { > pr_err("set VMSA page failed (%u)\n", ret); > free_page((unsigned long)vmsa); > @@ -1193,7 +1234,10 @@ static int wakeup_cpu_via_vmgexit(u32 apic_id, unsigned long start_ip) > vc_ghcb_invalidate(ghcb); > ghcb_set_rax(ghcb, vmsa->sev_features); > ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_AP_CREATION); > - ghcb_set_sw_exit_info_1(ghcb, ((u64)apic_id << 32) | SVM_VMGEXIT_AP_CREATE); > + ghcb_set_sw_exit_info_1(ghcb, > + ((u64)apic_id << 32) | > + ((u64)vmpl << 16) | > + SVM_VMGEXIT_AP_CREATE); > ghcb_set_sw_exit_info_2(ghcb, __pa(vmsa)); > > sev_es_wr_ghcb_msr(__pa(ghcb)); > @@ -1211,13 +1255,13 @@ static int wakeup_cpu_via_vmgexit(u32 apic_id, unsigned long start_ip) > > /* Perform cleanup if there was an error */ > if (ret) { > - snp_cleanup_vmsa(vmsa); > + snp_cleanup_vmsa(vmsa, apic_id); > vmsa = NULL; > } > > /* Free up any previous VMSA page */ > if (cur_vmsa) > - snp_cleanup_vmsa(cur_vmsa); > + snp_cleanup_vmsa(cur_vmsa, apic_id); > > /* Record the current VMSA page */ > per_cpu(sev_vmsa, cpu) = vmsa;
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