Messages in this thread Patch in this message | | | Date | Wed, 17 Aug 2022 18:08:19 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH v3 1/2] x86/sev: Put PSC struct on the stack in prep for unaccepted memory support |
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On Mon, Aug 15, 2022 at 10:57:42AM -0500, Tom Lendacky wrote: > diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c > index c05f0124c410..40268ce97aad 100644 > --- a/arch/x86/kernel/sev.c > +++ b/arch/x86/kernel/sev.c > @@ -66,6 +66,17 @@ static struct ghcb boot_ghcb_page __bss_decrypted __aligned(PAGE_SIZE); > */ > static struct ghcb *boot_ghcb __section(".data"); > > +/* > + * A flag used by set_pages_state() that indicates when the per-CPU GHCB has > + * been created and registered and thus can be used instead of using the MSR > + * protocol. The set_pages_state() function eventually invokes vmgexit_psc(), > + * which only works with a per-CPU GHCB. > + * > + * For APs, the per-CPU GHCB is created before they are started and registered > + * upon startup, so this flag can be used globally for the BSP and APs. > + */
Ok, better, thanks!
> +static bool ghcb_percpu_ready __section(".data");
However, it reads really weird if you have "percpu" in the name of a variable which is not per CPU...
Let's just call it "ghcbs_initialized" and be done with it.
And I still hate the whole thing ofc.
Do this ontop (and I knew we had a flags thing already):
(And yes, __read_mostly is in the .data section too).
--- diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index 40268ce97aad..5b3afbf26349 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -66,17 +66,6 @@ static struct ghcb boot_ghcb_page __bss_decrypted __aligned(PAGE_SIZE); */ static struct ghcb *boot_ghcb __section(".data"); -/* - * A flag used by set_pages_state() that indicates when the per-CPU GHCB has - * been created and registered and thus can be used instead of using the MSR - * protocol. The set_pages_state() function eventually invokes vmgexit_psc(), - * which only works with a per-CPU GHCB. - * - * For APs, the per-CPU GHCB is created before they are started and registered - * upon startup, so this flag can be used globally for the BSP and APs. - */ -static bool ghcb_percpu_ready __section(".data"); - /* Bitmap of SEV features supported by the hypervisor */ static u64 sev_hv_features __ro_after_init; @@ -128,7 +117,18 @@ static DEFINE_PER_CPU(struct sev_es_save_area *, sev_vmsa); struct sev_config { __u64 debug : 1, - __reserved : 63; + + /* + * A flag used by set_pages_state() that indicates when the per-CPU GHCB has + * been created and registered and thus can be used instead of using the MSR + * protocol. The set_pages_state() function eventually invokes vmgexit_psc(), + * which only works with a per-CPU GHCB. + * + * For APs, the per-CPU GHCB is created before they are started and registered + * upon startup, so this flag can be used globally for the BSP and APs. + */ + ghcbs_initialized : 1, + __reserved : 62; }; static struct sev_config sev_cfg __read_mostly; @@ -762,7 +762,7 @@ static int vmgexit_psc(struct snp_psc_desc *desc) unsigned long flags; struct ghcb *ghcb; - WARN_ON_ONCE(!ghcb_percpu_ready); + WARN_ON_ONCE(!sev_cfg.ghcbs_initialized); /* * __sev_get_ghcb() needs to run with IRQs disabled because it is using @@ -887,7 +887,7 @@ static void set_pages_state(unsigned long vaddr, unsigned int npages, int op) * Use the MSR protocol when the per-CPU GHCBs are not yet registered, * since vmgexit_psc() uses the per-CPU GHCB. */ - if (!ghcb_percpu_ready) + if (!sev_cfg.ghcbs_initialized) return early_set_pages_state(__pa(vaddr), npages, op); vaddr = vaddr & PAGE_MASK; @@ -1268,7 +1268,7 @@ void setup_ghcb(void) if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) snp_register_per_cpu_ghcb(); - ghcb_percpu_ready = true; + sev_cfg.ghcbs_initialized = true; return; } -- Regards/Gruss, Boris.
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