| Message ID | 20210602140416.23573-20-brijesh.singh@amd.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Add AMD Secure Nested Paging (SEV-SNP) Guest Support | expand |
On Wed, Jun 02, 2021 at 09:04:13AM -0500, Brijesh Singh wrote: > From: Tom Lendacky <thomas.lendacky@amd.com> > Subject: Re: [PATCH Part1 RFC v3 19/22] x86/sev-snp: SEV-SNP AP creation support The condensed patch description in the subject line should be written in imperative tone. I.e., it needs a verb. And to simplify it even more, let's prefix all SEV-* stuff with "x86/sev: " from now on to mean the whole encrypted virt area. > To provide a more secure way to start APs under SEV-SNP, use the SEV-SNP > AP Creation NAE event. This allows for guest control over the AP register > state rather than trusting the hypervisor with the SEV-ES Jump Table > address. > > During native_smp_prepare_cpus(), invoke an SEV-SNP function that, if > SEV-SNP is active, will set or override apic->wakeup_secondary_cpu. This > will allow the SEV-SNP AP Creation NAE event method to be used to boot > the APs. > > Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> > Signed-off-by: Brijesh Singh <brijesh.singh@amd.com> > --- > arch/x86/include/asm/sev-common.h | 1 + > arch/x86/include/asm/sev.h | 13 ++ > arch/x86/include/uapi/asm/svm.h | 5 + > arch/x86/kernel/sev-shared.c | 5 + > arch/x86/kernel/sev.c | 206 ++++++++++++++++++++++++++++++ > arch/x86/kernel/smpboot.c | 3 + > 6 files changed, 233 insertions(+) > > diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h > index 86bb185b5ec1..47aa57bf654a 100644 > --- a/arch/x86/include/asm/sev-common.h > +++ b/arch/x86/include/asm/sev-common.h > @@ -57,6 +57,7 @@ > (((unsigned long)((v) & GHCB_MSR_HV_FT_MASK) >> GHCB_MSR_HV_FT_POS)) > > #define GHCB_HV_FT_SNP BIT_ULL(0) > +#define GHCB_HV_FT_SNP_AP_CREATION (BIT_ULL(1) | GHCB_HV_FT_SNP) > > /* SNP Page State Change */ > #define GHCB_MSR_PSC_REQ 0x014 > diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h > index e2141fc28058..640108402ae9 100644 > --- a/arch/x86/include/asm/sev.h > +++ b/arch/x86/include/asm/sev.h > @@ -71,6 +71,13 @@ enum snp_mem_op { > MEMORY_SHARED > }; > > +#define RMPADJUST_VMPL_MAX 3 > +#define RMPADJUST_VMPL_MASK GENMASK(7, 0) > +#define RMPADJUST_VMPL_SHIFT 0 > +#define RMPADJUST_PERM_MASK_MASK GENMASK(7, 0) mask mask huh? How about "perm mask" and "perm shift" ? > +#define RMPADJUST_PERM_MASK_SHIFT 8 > +#define RMPADJUST_VMSA_PAGE_BIT BIT(16) > + > #ifdef CONFIG_AMD_MEM_ENCRYPT > extern struct static_key_false sev_es_enable_key; > extern void __sev_es_ist_enter(struct pt_regs *regs); > @@ -116,6 +123,9 @@ void __init early_snp_set_memory_shared(unsigned long vaddr, unsigned long paddr > void __init snp_prep_memory(unsigned long paddr, unsigned int sz, int op); > void snp_set_memory_shared(unsigned long vaddr, unsigned int npages); > void snp_set_memory_private(unsigned long vaddr, unsigned int npages); > + No need for the newlines here - it is all function prototypes lumped together - the only one who reads them is the compiler. > +void snp_setup_wakeup_secondary_cpu(void); "setup" "wakeup" huh? snp_set_wakeup_secondary_cpu() looks just fine to me. :) > diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c > index b62226bf51b9..7139c9ba59b2 100644 > --- a/arch/x86/kernel/sev-shared.c > +++ b/arch/x86/kernel/sev-shared.c > @@ -32,6 +32,11 @@ static bool __init sev_es_check_cpu_features(void) > return true; > } > > +static bool snp_ap_creation_supported(void) > +{ > + return (hv_features & GHCB_HV_FT_SNP_AP_CREATION) == GHCB_HV_FT_SNP_AP_CREATION; > +} Can we get rid of those silly accessors pls? We established earlier that hv_features is going to be __ro_after_init so we might just as well export it to sev.c for direct querying - there's no worry that something'll change it during runtime. > static bool __init sev_snp_check_hypervisor_features(void) > { > if (ghcb_version < 2) > diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c > index 4847ac81cca3..8f7ef35a25ef 100644 > --- a/arch/x86/kernel/sev.c > +++ b/arch/x86/kernel/sev.c > @@ -19,6 +19,7 @@ > #include <linux/memblock.h> > #include <linux/kernel.h> > #include <linux/mm.h> > +#include <linux/cpumask.h> > > #include <asm/cpu_entry_area.h> > #include <asm/stacktrace.h> > @@ -31,6 +32,7 @@ > #include <asm/svm.h> > #include <asm/smp.h> > #include <asm/cpu.h> > +#include <asm/apic.h> > > #include "sev-internal.h" > > @@ -106,6 +108,8 @@ struct ghcb_state { > static DEFINE_PER_CPU(struct sev_es_runtime_data*, runtime_data); > DEFINE_STATIC_KEY_FALSE(sev_es_enable_key); > > +static DEFINE_PER_CPU(struct sev_es_save_area *, snp_vmsa); > + > /* Needed in vc_early_forward_exception */ > void do_early_exception(struct pt_regs *regs, int trapnr); > > @@ -744,6 +748,208 @@ void snp_set_memory_private(unsigned long vaddr, unsigned int npages) > pvalidate_pages(vaddr, npages, 1); > } > > +static int snp_rmpadjust(void *va, unsigned int vmpl, unsigned int perm_mask, bool vmsa) No need for the "snp_" prefix. Drop it for all static functions here too pls. @vmpl can be a u8 so that you don't need to mask it off. The same for @perm_mask. And then you can drop the mask defines too. > +{ > + unsigned int attrs; > + int err; > + > + attrs = (vmpl & RMPADJUST_VMPL_MASK) << RMPADJUST_VMPL_SHIFT; Shift by 0 huh? Can we drop this silliness pls? /* Make sure Reserved[63:17] is 0 */ attrs = 0; attrs |= vmpl; Plain and simple. > + attrs |= (perm_mask & RMPADJUST_PERM_MASK_MASK) << RMPADJUST_PERM_MASK_SHIFT; perm_mask is always 0 - you don't even have to pass it in as a function argument. > + if (vmsa) > + attrs |= RMPADJUST_VMSA_PAGE_BIT; > + > + /* Perform RMPADJUST */ Add: /* Instruction mnemonic supported in binutils versions v2.36 and later */ > + asm volatile (".byte 0xf3,0x0f,0x01,0xfe\n\t" > + : "=a" (err) here you should do: : ... "c" (RMP_PG_SIZE_4K), ... so that it is clear what goes into %rcx. > + : "a" (va), "c" (0), "d" (attrs) > + : "memory", "cc"); > + > + return err; > +} > + > +static int snp_clear_vmsa(void *vmsa) > +{ > + /* > + * Clear the VMSA attribute for the page: > + * RDX[7:0] = 1, Target VMPL level, must be numerically > + * higher than current level (VMPL0) But RMPADJUST_VMPL_MAX is 3?! > + * RDX[15:8] = 0, Target permission mask (not used) > + * RDX[16] = 0, Not a VMSA page > + */ > + return snp_rmpadjust(vmsa, RMPADJUST_VMPL_MAX, 0, false); > +} > + > +static int snp_set_vmsa(void *vmsa) > +{ > + /* > + * To set the VMSA attribute for the page: > + * RDX[7:0] = 1, Target VMPL level, must be numerically > + * higher than current level (VMPL0) > + * RDX[15:8] = 0, Target permission mask (not used) > + * RDX[16] = 1, VMSA page > + */ > + return snp_rmpadjust(vmsa, RMPADJUST_VMPL_MAX, 0, true); > +} > + > +#define INIT_CS_ATTRIBS (SVM_SELECTOR_P_MASK | SVM_SELECTOR_S_MASK | SVM_SELECTOR_READ_MASK | SVM_SELECTOR_CODE_MASK) > +#define INIT_DS_ATTRIBS (SVM_SELECTOR_P_MASK | SVM_SELECTOR_S_MASK | SVM_SELECTOR_WRITE_MASK) > + Put SVM_SELECTOR_P_MASK | SVM_SELECTOR_S_MASK in a helper define and share it in the two definitions above pls. > +#define INIT_LDTR_ATTRIBS (SVM_SELECTOR_P_MASK | 2) > +#define INIT_TR_ATTRIBS (SVM_SELECTOR_P_MASK | 3) > + > +static int snp_wakeup_cpu_via_vmgexit(int apic_id, unsigned long start_ip) > +{ > + struct sev_es_save_area *cur_vmsa; > + struct sev_es_save_area *vmsa; > + struct ghcb_state state; > + struct ghcb *ghcb; > + unsigned long flags; > + u8 sipi_vector; > + u64 cr4; > + int cpu; > + int ret; Remember the reversed xmas tree. And you can combine the variables of the same type into a single line. > + > + if (!snp_ap_creation_supported()) > + return -ENOTSUPP; WARNING: ENOTSUPP is not a SUSV4 error code, prefer EOPNOTSUPP #320: FILE: arch/x86/kernel/sev.c:813: + return -ENOTSUPP; > + /* Override start_ip with known SEV-ES/SEV-SNP starting RIP */ > + if (start_ip == real_mode_header->trampoline_start) { > + start_ip = real_mode_header->sev_es_trampoline_start; > + } else { > + WARN_ONCE(1, "unsupported SEV-SNP start_ip: %lx\n", start_ip); > + return -EINVAL; > + } What's all that checking for? Why not simply and unconditionally doing: start_ip = real_mode_header->sev_es_trampoline_start; ? We are waking up an SNP guest so who cares what the previous start_ip value was? > + /* Find the logical CPU for the APIC ID */ > + for_each_present_cpu(cpu) { > + if (arch_match_cpu_phys_id(cpu, apic_id)) > + break; > + } > + if (cpu >= nr_cpu_ids) > + return -EINVAL; > + > + cur_vmsa = per_cpu(snp_vmsa, cpu); Where is that snp_vmsa thing used? I don't see it anywhere in the whole patchset. > + vmsa = (struct sev_es_save_area *)get_zeroed_page(GFP_KERNEL); > + if (!vmsa) > + return -ENOMEM; > + > + /* CR4 should maintain the MCE value */ > + cr4 = native_read_cr4() & ~X86_CR4_MCE; > + > + /* Set the CS value based on the start_ip converted to a SIPI vector */ > + sipi_vector = (start_ip >> 12); > + vmsa->cs.base = sipi_vector << 12; > + vmsa->cs.limit = 0xffff; > + vmsa->cs.attrib = INIT_CS_ATTRIBS; > + vmsa->cs.selector = sipi_vector << 8; > + > + /* Set the RIP value based on start_ip */ > + vmsa->rip = start_ip & 0xfff; > + > + /* Set VMSA entries to the INIT values as documented in the APM */ > + vmsa->ds.limit = 0xffff; > + vmsa->ds.attrib = INIT_DS_ATTRIBS; > + vmsa->es = vmsa->ds; > + vmsa->fs = vmsa->ds; > + vmsa->gs = vmsa->ds; > + vmsa->ss = vmsa->ds; > + > + vmsa->gdtr.limit = 0xffff; > + vmsa->ldtr.limit = 0xffff; > + vmsa->ldtr.attrib = INIT_LDTR_ATTRIBS; > + vmsa->idtr.limit = 0xffff; > + vmsa->tr.limit = 0xffff; > + vmsa->tr.attrib = INIT_TR_ATTRIBS; > + > + vmsa->efer = 0x1000; /* Must set SVME bit */ > + vmsa->cr4 = cr4; > + vmsa->cr0 = 0x60000010; > + vmsa->dr7 = 0x400; > + vmsa->dr6 = 0xffff0ff0; > + vmsa->rflags = 0x2; > + vmsa->g_pat = 0x0007040600070406ULL; > + vmsa->xcr0 = 0x1; > + vmsa->mxcsr = 0x1f80; > + vmsa->x87_ftw = 0x5555; > + vmsa->x87_fcw = 0x0040; Align them all on a single vertical line pls. > + /* > + * Set the SNP-specific fields for this VMSA: > + * VMPL level > + * SEV_FEATURES (matches the SEV STATUS MSR right shifted 2 bits) > + */ > + vmsa->vmpl = 0; > + vmsa->sev_features = sev_status >> 2; > + > + /* Switch the page over to a VMSA page now that it is initialized */ > + ret = snp_set_vmsa(vmsa); > + if (ret) { > + pr_err("set VMSA page failed (%u)\n", ret); > + free_page((unsigned long)vmsa); > + > + return -EINVAL; > + } > + > + /* Issue VMGEXIT AP Creation NAE event */ > + local_irq_save(flags); > + > + ghcb = sev_es_get_ghcb(&state); > + > + 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_2(ghcb, __pa(vmsa)); > + > + sev_es_wr_ghcb_msr(__pa(ghcb)); > + VMGEXIT(); > + > + if (!ghcb_sw_exit_info_1_is_valid(ghcb) || > + lower_32_bits(ghcb->save.sw_exit_info_1)) { > + pr_alert("SNP AP Creation error\n"); > + ret = -EINVAL; > + } > + > + sev_es_put_ghcb(&state); > + > + local_irq_restore(flags); > + > + /* Perform cleanup if there was an error */ > + if (ret) { > + int err = snp_clear_vmsa(vmsa); > + ^ Superfluous newline. > + if (err) > + pr_err("clear VMSA page failed (%u), leaking page\n", err); > + else > + free_page((unsigned long)vmsa); > + > + vmsa = NULL; > + } > + > + /* Free up any previous VMSA page */ > + if (cur_vmsa) { > + int err = snp_clear_vmsa(cur_vmsa); > + ^ Superfluous newline. > + if (err) > + pr_err("clear VMSA page failed (%u), leaking page\n", err); > + else > + free_page((unsigned long)cur_vmsa); > + } > + > + /* Record the current VMSA page */ > + cur_vmsa = vmsa; > + > + return ret; > +}
On 6/16/21 8:07 AM, Borislav Petkov wrote: > On Wed, Jun 02, 2021 at 09:04:13AM -0500, Brijesh Singh wrote: >> From: Tom Lendacky <thomas.lendacky@amd.com> > >> Subject: Re: [PATCH Part1 RFC v3 19/22] x86/sev-snp: SEV-SNP AP creation support > > The condensed patch description in the subject line should be written in > imperative tone. I.e., it needs a verb. > > And to simplify it even more, let's prefix all SEV-* stuff with > "x86/sev: " from now on to mean the whole encrypted virt area. Yup, I'll make those changes. > >> To provide a more secure way to start APs under SEV-SNP, use the SEV-SNP >> AP Creation NAE event. This allows for guest control over the AP register >> state rather than trusting the hypervisor with the SEV-ES Jump Table >> address. >> >> During native_smp_prepare_cpus(), invoke an SEV-SNP function that, if >> SEV-SNP is active, will set or override apic->wakeup_secondary_cpu. This >> will allow the SEV-SNP AP Creation NAE event method to be used to boot >> the APs. >> >> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> >> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com> >> --- >> arch/x86/include/asm/sev-common.h | 1 + >> arch/x86/include/asm/sev.h | 13 ++ >> arch/x86/include/uapi/asm/svm.h | 5 + >> arch/x86/kernel/sev-shared.c | 5 + >> arch/x86/kernel/sev.c | 206 ++++++++++++++++++++++++++++++ >> arch/x86/kernel/smpboot.c | 3 + >> 6 files changed, 233 insertions(+) >> >> diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h >> index 86bb185b5ec1..47aa57bf654a 100644 >> --- a/arch/x86/include/asm/sev-common.h >> +++ b/arch/x86/include/asm/sev-common.h >> @@ -57,6 +57,7 @@ >> (((unsigned long)((v) & GHCB_MSR_HV_FT_MASK) >> GHCB_MSR_HV_FT_POS)) >> >> #define GHCB_HV_FT_SNP BIT_ULL(0) >> +#define GHCB_HV_FT_SNP_AP_CREATION (BIT_ULL(1) | GHCB_HV_FT_SNP) >> >> /* SNP Page State Change */ >> #define GHCB_MSR_PSC_REQ 0x014 >> diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h >> index e2141fc28058..640108402ae9 100644 >> --- a/arch/x86/include/asm/sev.h >> +++ b/arch/x86/include/asm/sev.h >> @@ -71,6 +71,13 @@ enum snp_mem_op { >> MEMORY_SHARED >> }; >> >> +#define RMPADJUST_VMPL_MAX 3 >> +#define RMPADJUST_VMPL_MASK GENMASK(7, 0) >> +#define RMPADJUST_VMPL_SHIFT 0 >> +#define RMPADJUST_PERM_MASK_MASK GENMASK(7, 0) > > mask mask huh? > > How about "perm mask" and "perm shift" ? Yeah, I debated on that one. I wanted to stay close to what the APM has, which is PERM_MASK (TARGET_PERM_MASK actually), but it does look odd. I'll get rid of the MASK portion of PERM_MASK. > >> +#define RMPADJUST_PERM_MASK_SHIFT 8 >> +#define RMPADJUST_VMSA_PAGE_BIT BIT(16) >> + >> #ifdef CONFIG_AMD_MEM_ENCRYPT >> extern struct static_key_false sev_es_enable_key; >> extern void __sev_es_ist_enter(struct pt_regs *regs); >> @@ -116,6 +123,9 @@ void __init early_snp_set_memory_shared(unsigned long vaddr, unsigned long paddr >> void __init snp_prep_memory(unsigned long paddr, unsigned int sz, int op); >> void snp_set_memory_shared(unsigned long vaddr, unsigned int npages); >> void snp_set_memory_private(unsigned long vaddr, unsigned int npages); >> + > > No need for the newlines here - it is all function prototypes lumped > together - the only one who reads them is the compiler. > >> +void snp_setup_wakeup_secondary_cpu(void); > > "setup" "wakeup" huh? > > snp_set_wakeup_secondary_cpu() looks just fine to me. :) Will do. > >> diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c >> index b62226bf51b9..7139c9ba59b2 100644 >> --- a/arch/x86/kernel/sev-shared.c >> +++ b/arch/x86/kernel/sev-shared.c >> @@ -32,6 +32,11 @@ static bool __init sev_es_check_cpu_features(void) >> return true; >> } >> >> +static bool snp_ap_creation_supported(void) >> +{ >> + return (hv_features & GHCB_HV_FT_SNP_AP_CREATION) == GHCB_HV_FT_SNP_AP_CREATION; >> +} > > Can we get rid of those silly accessors pls? Will do. > > We established earlier that hv_features is going to be __ro_after_init > so we might just as well export it to sev.c for direct querying - > there's no worry that something'll change it during runtime. > >> static bool __init sev_snp_check_hypervisor_features(void) >> { >> if (ghcb_version < 2) >> diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c >> index 4847ac81cca3..8f7ef35a25ef 100644 >> --- a/arch/x86/kernel/sev.c >> +++ b/arch/x86/kernel/sev.c >> @@ -19,6 +19,7 @@ >> #include <linux/memblock.h> >> #include <linux/kernel.h> >> #include <linux/mm.h> >> +#include <linux/cpumask.h> >> >> #include <asm/cpu_entry_area.h> >> #include <asm/stacktrace.h> >> @@ -31,6 +32,7 @@ >> #include <asm/svm.h> >> #include <asm/smp.h> >> #include <asm/cpu.h> >> +#include <asm/apic.h> >> >> #include "sev-internal.h" >> >> @@ -106,6 +108,8 @@ struct ghcb_state { >> static DEFINE_PER_CPU(struct sev_es_runtime_data*, runtime_data); >> DEFINE_STATIC_KEY_FALSE(sev_es_enable_key); >> >> +static DEFINE_PER_CPU(struct sev_es_save_area *, snp_vmsa); >> + >> /* Needed in vc_early_forward_exception */ >> void do_early_exception(struct pt_regs *regs, int trapnr); >> >> @@ -744,6 +748,208 @@ void snp_set_memory_private(unsigned long vaddr, unsigned int npages) >> pvalidate_pages(vaddr, npages, 1); >> } >> >> +static int snp_rmpadjust(void *va, unsigned int vmpl, unsigned int perm_mask, bool vmsa) > > No need for the "snp_" prefix. Drop it for all static functions here too > pls. > > @vmpl can be a u8 so that you don't need to mask it off. The same for > @perm_mask. And then you can drop the mask defines too. Will do. > >> +{ >> + unsigned int attrs; >> + int err; >> + >> + attrs = (vmpl & RMPADJUST_VMPL_MASK) << RMPADJUST_VMPL_SHIFT; > > Shift by 0 huh? Can we drop this silliness pls? > > /* Make sure Reserved[63:17] is 0 */ > attrs = 0; > > attrs |= vmpl; > > Plain and simple. > >> + attrs |= (perm_mask & RMPADJUST_PERM_MASK_MASK) << RMPADJUST_PERM_MASK_SHIFT; > > perm_mask is always 0 - you don't even have to pass it in as a function > argument. Will do. The compiler should be smart enough to do the right thing, I was just trying to show the structure of the input. But, easy enough to drop it. > >> + if (vmsa) >> + attrs |= RMPADJUST_VMSA_PAGE_BIT; >> + >> + /* Perform RMPADJUST */ > > Add: > > /* Instruction mnemonic supported in binutils versions v2.36 and later */ Will do. > >> + asm volatile (".byte 0xf3,0x0f,0x01,0xfe\n\t" >> + : "=a" (err) > > here you should do: > > : ... "c" (RMP_PG_SIZE_4K), ... > > so that it is clear what goes into %rcx. Will do. > >> + : "a" (va), "c" (0), "d" (attrs) >> + : "memory", "cc"); >> + >> + return err; >> +} >> + >> +static int snp_clear_vmsa(void *vmsa) >> +{ >> + /* >> + * Clear the VMSA attribute for the page: >> + * RDX[7:0] = 1, Target VMPL level, must be numerically >> + * higher than current level (VMPL0) > > But RMPADJUST_VMPL_MAX is 3?! Yup, I'll make this change. And actually, the max VMPL is defined via CPUID, so I may look at saving that off somewhere or just retrieve it here and use that. > >> + * RDX[15:8] = 0, Target permission mask (not used) >> + * RDX[16] = 0, Not a VMSA page >> + */ >> + return snp_rmpadjust(vmsa, RMPADJUST_VMPL_MAX, 0, false); >> +} >> + >> +static int snp_set_vmsa(void *vmsa) >> +{ >> + /* >> + * To set the VMSA attribute for the page: >> + * RDX[7:0] = 1, Target VMPL level, must be numerically >> + * higher than current level (VMPL0) >> + * RDX[15:8] = 0, Target permission mask (not used) >> + * RDX[16] = 1, VMSA page >> + */ >> + return snp_rmpadjust(vmsa, RMPADJUST_VMPL_MAX, 0, true); >> +} >> + >> +#define INIT_CS_ATTRIBS (SVM_SELECTOR_P_MASK | SVM_SELECTOR_S_MASK | SVM_SELECTOR_READ_MASK | SVM_SELECTOR_CODE_MASK) >> +#define INIT_DS_ATTRIBS (SVM_SELECTOR_P_MASK | SVM_SELECTOR_S_MASK | SVM_SELECTOR_WRITE_MASK) >> + > > Put SVM_SELECTOR_P_MASK | SVM_SELECTOR_S_MASK in a helper define and share it in the two > definitions above pls. Will do. > >> +#define INIT_LDTR_ATTRIBS (SVM_SELECTOR_P_MASK | 2) >> +#define INIT_TR_ATTRIBS (SVM_SELECTOR_P_MASK | 3) >> + >> +static int snp_wakeup_cpu_via_vmgexit(int apic_id, unsigned long start_ip) >> +{ >> + struct sev_es_save_area *cur_vmsa; >> + struct sev_es_save_area *vmsa; >> + struct ghcb_state state; >> + struct ghcb *ghcb; >> + unsigned long flags; >> + u8 sipi_vector; >> + u64 cr4; >> + int cpu; >> + int ret; > > Remember the reversed xmas tree. And you can combine the variables of > the same type into a single line. Yup. > >> + >> + if (!snp_ap_creation_supported()) >> + return -ENOTSUPP; > > WARNING: ENOTSUPP is not a SUSV4 error code, prefer EOPNOTSUPP > #320: FILE: arch/x86/kernel/sev.c:813: > + return -ENOTSUPP; Yup. > >> + /* Override start_ip with known SEV-ES/SEV-SNP starting RIP */ >> + if (start_ip == real_mode_header->trampoline_start) { >> + start_ip = real_mode_header->sev_es_trampoline_start; >> + } else { >> + WARN_ONCE(1, "unsupported SEV-SNP start_ip: %lx\n", start_ip); >> + return -EINVAL; >> + } > > What's all that checking for? Why not simply and unconditionally doing: > > start_ip = real_mode_header->sev_es_trampoline_start; > > ? > > We are waking up an SNP guest so who cares what the previous start_ip > value was? It is to catch any change in the future that adds a new trampoline start location, that may do something different. If that happens, then this will do the wrong thing, so it's just a safe guard. > >> + /* Find the logical CPU for the APIC ID */ >> + for_each_present_cpu(cpu) { >> + if (arch_match_cpu_phys_id(cpu, apic_id)) >> + break; >> + } >> + if (cpu >= nr_cpu_ids) >> + return -EINVAL; >> + >> + cur_vmsa = per_cpu(snp_vmsa, cpu); > > Where is that snp_vmsa thing used? I don't see it anywhere in the whole > patchset. Ah, good catch. It should be set at the end of the function in place of the "cur_vmsa = vmsa" statement. > >> + vmsa = (struct sev_es_save_area *)get_zeroed_page(GFP_KERNEL); >> + if (!vmsa) >> + return -ENOMEM; >> + >> + /* CR4 should maintain the MCE value */ >> + cr4 = native_read_cr4() & ~X86_CR4_MCE; >> + >> + /* Set the CS value based on the start_ip converted to a SIPI vector */ >> + sipi_vector = (start_ip >> 12); >> + vmsa->cs.base = sipi_vector << 12; >> + vmsa->cs.limit = 0xffff; >> + vmsa->cs.attrib = INIT_CS_ATTRIBS; >> + vmsa->cs.selector = sipi_vector << 8; >> + >> + /* Set the RIP value based on start_ip */ >> + vmsa->rip = start_ip & 0xfff; >> + >> + /* Set VMSA entries to the INIT values as documented in the APM */ >> + vmsa->ds.limit = 0xffff; >> + vmsa->ds.attrib = INIT_DS_ATTRIBS; >> + vmsa->es = vmsa->ds; >> + vmsa->fs = vmsa->ds; >> + vmsa->gs = vmsa->ds; >> + vmsa->ss = vmsa->ds; >> + >> + vmsa->gdtr.limit = 0xffff; >> + vmsa->ldtr.limit = 0xffff; >> + vmsa->ldtr.attrib = INIT_LDTR_ATTRIBS; >> + vmsa->idtr.limit = 0xffff; >> + vmsa->tr.limit = 0xffff; >> + vmsa->tr.attrib = INIT_TR_ATTRIBS; >> + >> + vmsa->efer = 0x1000; /* Must set SVME bit */ >> + vmsa->cr4 = cr4; >> + vmsa->cr0 = 0x60000010; >> + vmsa->dr7 = 0x400; >> + vmsa->dr6 = 0xffff0ff0; >> + vmsa->rflags = 0x2; >> + vmsa->g_pat = 0x0007040600070406ULL; >> + vmsa->xcr0 = 0x1; >> + vmsa->mxcsr = 0x1f80; >> + vmsa->x87_ftw = 0x5555; >> + vmsa->x87_fcw = 0x0040; > > Align them all on a single vertical line pls. Will do. > >> + /* >> + * Set the SNP-specific fields for this VMSA: >> + * VMPL level >> + * SEV_FEATURES (matches the SEV STATUS MSR right shifted 2 bits) >> + */ >> + vmsa->vmpl = 0; >> + vmsa->sev_features = sev_status >> 2; >> + >> + /* Switch the page over to a VMSA page now that it is initialized */ >> + ret = snp_set_vmsa(vmsa); >> + if (ret) { >> + pr_err("set VMSA page failed (%u)\n", ret); >> + free_page((unsigned long)vmsa); >> + >> + return -EINVAL; >> + } >> + >> + /* Issue VMGEXIT AP Creation NAE event */ >> + local_irq_save(flags); >> + >> + ghcb = sev_es_get_ghcb(&state); >> + >> + 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_2(ghcb, __pa(vmsa)); >> + >> + sev_es_wr_ghcb_msr(__pa(ghcb)); >> + VMGEXIT(); >> + >> + if (!ghcb_sw_exit_info_1_is_valid(ghcb) || >> + lower_32_bits(ghcb->save.sw_exit_info_1)) { >> + pr_alert("SNP AP Creation error\n"); >> + ret = -EINVAL; >> + } >> + >> + sev_es_put_ghcb(&state); >> + >> + local_irq_restore(flags); >> + >> + /* Perform cleanup if there was an error */ >> + if (ret) { >> + int err = snp_clear_vmsa(vmsa); >> + > > > ^ Superfluous newline. Ok. > >> + if (err) >> + pr_err("clear VMSA page failed (%u), leaking page\n", err); >> + else >> + free_page((unsigned long)vmsa); >> + >> + vmsa = NULL; >> + } >> + >> + /* Free up any previous VMSA page */ >> + if (cur_vmsa) { >> + int err = snp_clear_vmsa(cur_vmsa); >> + > > > ^ Superfluous newline. Ok. Thanks, Tom > >> + if (err) >> + pr_err("clear VMSA page failed (%u), leaking page\n", err); >> + else >> + free_page((unsigned long)cur_vmsa); >> + } >> + >> + /* Record the current VMSA page */ >> + cur_vmsa = vmsa; >> + >> + return ret; >> +} >
diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h index 86bb185b5ec1..47aa57bf654a 100644 --- a/arch/x86/include/asm/sev-common.h +++ b/arch/x86/include/asm/sev-common.h @@ -57,6 +57,7 @@ (((unsigned long)((v) & GHCB_MSR_HV_FT_MASK) >> GHCB_MSR_HV_FT_POS)) #define GHCB_HV_FT_SNP BIT_ULL(0) +#define GHCB_HV_FT_SNP_AP_CREATION (BIT_ULL(1) | GHCB_HV_FT_SNP) /* SNP Page State Change */ #define GHCB_MSR_PSC_REQ 0x014 diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index e2141fc28058..640108402ae9 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -71,6 +71,13 @@ enum snp_mem_op { MEMORY_SHARED }; +#define RMPADJUST_VMPL_MAX 3 +#define RMPADJUST_VMPL_MASK GENMASK(7, 0) +#define RMPADJUST_VMPL_SHIFT 0 +#define RMPADJUST_PERM_MASK_MASK GENMASK(7, 0) +#define RMPADJUST_PERM_MASK_SHIFT 8 +#define RMPADJUST_VMSA_PAGE_BIT BIT(16) + #ifdef CONFIG_AMD_MEM_ENCRYPT extern struct static_key_false sev_es_enable_key; extern void __sev_es_ist_enter(struct pt_regs *regs); @@ -116,6 +123,9 @@ void __init early_snp_set_memory_shared(unsigned long vaddr, unsigned long paddr void __init snp_prep_memory(unsigned long paddr, unsigned int sz, int op); void snp_set_memory_shared(unsigned long vaddr, unsigned int npages); void snp_set_memory_private(unsigned long vaddr, unsigned int npages); + +void snp_setup_wakeup_secondary_cpu(void); + #else static inline void sev_es_ist_enter(struct pt_regs *regs) { } static inline void sev_es_ist_exit(void) { } @@ -134,6 +144,9 @@ early_snp_set_memory_shared(unsigned long vaddr, unsigned long paddr, unsigned i static inline void __init snp_prep_memory(unsigned long paddr, unsigned int sz, int op) { } static inline void snp_set_memory_shared(unsigned long vaddr, unsigned int npages) { } static inline void snp_set_memory_private(unsigned long vaddr, unsigned int npages) { } + +static inline void snp_setup_wakeup_secondary_cpu(void) { } + #endif #endif diff --git a/arch/x86/include/uapi/asm/svm.h b/arch/x86/include/uapi/asm/svm.h index 41573cf44470..c0152186a008 100644 --- a/arch/x86/include/uapi/asm/svm.h +++ b/arch/x86/include/uapi/asm/svm.h @@ -109,6 +109,10 @@ #define SVM_VMGEXIT_SET_AP_JUMP_TABLE 0 #define SVM_VMGEXIT_GET_AP_JUMP_TABLE 1 #define SVM_VMGEXIT_PSC 0x80000010 +#define SVM_VMGEXIT_AP_CREATION 0x80000013 +#define SVM_VMGEXIT_AP_CREATE_ON_INIT 0 +#define SVM_VMGEXIT_AP_CREATE 1 +#define SVM_VMGEXIT_AP_DESTROY 2 #define SVM_VMGEXIT_UNSUPPORTED_EVENT 0x8000ffff #define SVM_EXIT_ERR -1 @@ -217,6 +221,7 @@ { SVM_VMGEXIT_AP_HLT_LOOP, "vmgexit_ap_hlt_loop" }, \ { SVM_VMGEXIT_AP_JUMP_TABLE, "vmgexit_ap_jump_table" }, \ { SVM_VMGEXIT_PSC, "vmgexit_page_state_change" }, \ + { SVM_VMGEXIT_AP_CREATION, "vmgexit_ap_creation" }, \ { SVM_EXIT_ERR, "invalid_guest_state" } diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c index b62226bf51b9..7139c9ba59b2 100644 --- a/arch/x86/kernel/sev-shared.c +++ b/arch/x86/kernel/sev-shared.c @@ -32,6 +32,11 @@ static bool __init sev_es_check_cpu_features(void) return true; } +static bool snp_ap_creation_supported(void) +{ + return (hv_features & GHCB_HV_FT_SNP_AP_CREATION) == GHCB_HV_FT_SNP_AP_CREATION; +} + static bool __init sev_snp_check_hypervisor_features(void) { if (ghcb_version < 2) diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index 4847ac81cca3..8f7ef35a25ef 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -19,6 +19,7 @@ #include <linux/memblock.h> #include <linux/kernel.h> #include <linux/mm.h> +#include <linux/cpumask.h> #include <asm/cpu_entry_area.h> #include <asm/stacktrace.h> @@ -31,6 +32,7 @@ #include <asm/svm.h> #include <asm/smp.h> #include <asm/cpu.h> +#include <asm/apic.h> #include "sev-internal.h" @@ -106,6 +108,8 @@ struct ghcb_state { static DEFINE_PER_CPU(struct sev_es_runtime_data*, runtime_data); DEFINE_STATIC_KEY_FALSE(sev_es_enable_key); +static DEFINE_PER_CPU(struct sev_es_save_area *, snp_vmsa); + /* Needed in vc_early_forward_exception */ void do_early_exception(struct pt_regs *regs, int trapnr); @@ -744,6 +748,208 @@ void snp_set_memory_private(unsigned long vaddr, unsigned int npages) pvalidate_pages(vaddr, npages, 1); } +static int snp_rmpadjust(void *va, unsigned int vmpl, unsigned int perm_mask, bool vmsa) +{ + unsigned int attrs; + int err; + + attrs = (vmpl & RMPADJUST_VMPL_MASK) << RMPADJUST_VMPL_SHIFT; + attrs |= (perm_mask & RMPADJUST_PERM_MASK_MASK) << RMPADJUST_PERM_MASK_SHIFT; + if (vmsa) + attrs |= RMPADJUST_VMSA_PAGE_BIT; + + /* Perform RMPADJUST */ + asm volatile (".byte 0xf3,0x0f,0x01,0xfe\n\t" + : "=a" (err) + : "a" (va), "c" (0), "d" (attrs) + : "memory", "cc"); + + return err; +} + +static int snp_clear_vmsa(void *vmsa) +{ + /* + * Clear the VMSA attribute for the page: + * RDX[7:0] = 1, Target VMPL level, must be numerically + * higher than current level (VMPL0) + * RDX[15:8] = 0, Target permission mask (not used) + * RDX[16] = 0, Not a VMSA page + */ + return snp_rmpadjust(vmsa, RMPADJUST_VMPL_MAX, 0, false); +} + +static int snp_set_vmsa(void *vmsa) +{ + /* + * To set the VMSA attribute for the page: + * RDX[7:0] = 1, Target VMPL level, must be numerically + * higher than current level (VMPL0) + * RDX[15:8] = 0, Target permission mask (not used) + * RDX[16] = 1, VMSA page + */ + return snp_rmpadjust(vmsa, RMPADJUST_VMPL_MAX, 0, true); +} + +#define INIT_CS_ATTRIBS (SVM_SELECTOR_P_MASK | SVM_SELECTOR_S_MASK | SVM_SELECTOR_READ_MASK | SVM_SELECTOR_CODE_MASK) +#define INIT_DS_ATTRIBS (SVM_SELECTOR_P_MASK | SVM_SELECTOR_S_MASK | SVM_SELECTOR_WRITE_MASK) + +#define INIT_LDTR_ATTRIBS (SVM_SELECTOR_P_MASK | 2) +#define INIT_TR_ATTRIBS (SVM_SELECTOR_P_MASK | 3) + +static int snp_wakeup_cpu_via_vmgexit(int apic_id, unsigned long start_ip) +{ + struct sev_es_save_area *cur_vmsa; + struct sev_es_save_area *vmsa; + struct ghcb_state state; + struct ghcb *ghcb; + unsigned long flags; + u8 sipi_vector; + u64 cr4; + int cpu; + int ret; + + if (!snp_ap_creation_supported()) + return -ENOTSUPP; + + /* Override start_ip with known SEV-ES/SEV-SNP starting RIP */ + if (start_ip == real_mode_header->trampoline_start) { + start_ip = real_mode_header->sev_es_trampoline_start; + } else { + WARN_ONCE(1, "unsupported SEV-SNP start_ip: %lx\n", start_ip); + return -EINVAL; + } + + /* Find the logical CPU for the APIC ID */ + for_each_present_cpu(cpu) { + if (arch_match_cpu_phys_id(cpu, apic_id)) + break; + } + if (cpu >= nr_cpu_ids) + return -EINVAL; + + cur_vmsa = per_cpu(snp_vmsa, cpu); + vmsa = (struct sev_es_save_area *)get_zeroed_page(GFP_KERNEL); + if (!vmsa) + return -ENOMEM; + + /* CR4 should maintain the MCE value */ + cr4 = native_read_cr4() & ~X86_CR4_MCE; + + /* Set the CS value based on the start_ip converted to a SIPI vector */ + sipi_vector = (start_ip >> 12); + vmsa->cs.base = sipi_vector << 12; + vmsa->cs.limit = 0xffff; + vmsa->cs.attrib = INIT_CS_ATTRIBS; + vmsa->cs.selector = sipi_vector << 8; + + /* Set the RIP value based on start_ip */ + vmsa->rip = start_ip & 0xfff; + + /* Set VMSA entries to the INIT values as documented in the APM */ + vmsa->ds.limit = 0xffff; + vmsa->ds.attrib = INIT_DS_ATTRIBS; + vmsa->es = vmsa->ds; + vmsa->fs = vmsa->ds; + vmsa->gs = vmsa->ds; + vmsa->ss = vmsa->ds; + + vmsa->gdtr.limit = 0xffff; + vmsa->ldtr.limit = 0xffff; + vmsa->ldtr.attrib = INIT_LDTR_ATTRIBS; + vmsa->idtr.limit = 0xffff; + vmsa->tr.limit = 0xffff; + vmsa->tr.attrib = INIT_TR_ATTRIBS; + + vmsa->efer = 0x1000; /* Must set SVME bit */ + vmsa->cr4 = cr4; + vmsa->cr0 = 0x60000010; + vmsa->dr7 = 0x400; + vmsa->dr6 = 0xffff0ff0; + vmsa->rflags = 0x2; + vmsa->g_pat = 0x0007040600070406ULL; + vmsa->xcr0 = 0x1; + vmsa->mxcsr = 0x1f80; + vmsa->x87_ftw = 0x5555; + vmsa->x87_fcw = 0x0040; + + /* + * Set the SNP-specific fields for this VMSA: + * VMPL level + * SEV_FEATURES (matches the SEV STATUS MSR right shifted 2 bits) + */ + vmsa->vmpl = 0; + vmsa->sev_features = sev_status >> 2; + + /* Switch the page over to a VMSA page now that it is initialized */ + ret = snp_set_vmsa(vmsa); + if (ret) { + pr_err("set VMSA page failed (%u)\n", ret); + free_page((unsigned long)vmsa); + + return -EINVAL; + } + + /* Issue VMGEXIT AP Creation NAE event */ + local_irq_save(flags); + + ghcb = sev_es_get_ghcb(&state); + + 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_2(ghcb, __pa(vmsa)); + + sev_es_wr_ghcb_msr(__pa(ghcb)); + VMGEXIT(); + + if (!ghcb_sw_exit_info_1_is_valid(ghcb) || + lower_32_bits(ghcb->save.sw_exit_info_1)) { + pr_alert("SNP AP Creation error\n"); + ret = -EINVAL; + } + + sev_es_put_ghcb(&state); + + local_irq_restore(flags); + + /* Perform cleanup if there was an error */ + if (ret) { + int err = snp_clear_vmsa(vmsa); + + if (err) + pr_err("clear VMSA page failed (%u), leaking page\n", err); + else + free_page((unsigned long)vmsa); + + vmsa = NULL; + } + + /* Free up any previous VMSA page */ + if (cur_vmsa) { + int err = snp_clear_vmsa(cur_vmsa); + + if (err) + pr_err("clear VMSA page failed (%u), leaking page\n", err); + else + free_page((unsigned long)cur_vmsa); + } + + /* Record the current VMSA page */ + cur_vmsa = vmsa; + + return ret; +} + +void snp_setup_wakeup_secondary_cpu(void) +{ + if (!sev_feature_enabled(SEV_SNP)) + return; + + apic->wakeup_secondary_cpu = snp_wakeup_cpu_via_vmgexit; +} + int sev_es_setup_ap_jump_table(struct real_mode_header *rmh) { u16 startup_cs, startup_ip; diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 0ad5214f598a..973145081818 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -82,6 +82,7 @@ #include <asm/spec-ctrl.h> #include <asm/hw_irq.h> #include <asm/stackprotector.h> +#include <asm/sev.h> #ifdef CONFIG_ACPI_CPPC_LIB #include <acpi/cppc_acpi.h> @@ -1379,6 +1380,8 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus) smp_quirk_init_udelay(); speculative_store_bypass_ht_init(); + + snp_setup_wakeup_secondary_cpu(); } void arch_thaw_secondary_cpus_begin(void)