Guest context pages should be near 1-to-1 with allocated ASIDs. With the
GCTX API, the ccp driver is better able to associate guest context pages
with the ASID that is/will be bound to it.
This is important to the firmware hotloading implementation to not
corrupt any running VM's guest context page before userspace commits a
new firmware.
CC: Sean Christopherson <seanjc@google.com>
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Ingo Molnar <mingo@redhat.com>
CC: Borislav Petkov <bp@alien8.de>
CC: Dave Hansen <dave.hansen@linux.intel.com>
CC: Ashish Kalra <ashish.kalra@amd.com>
CC: Tom Lendacky <thomas.lendacky@amd.com>
CC: John Allen <john.allen@amd.com>
CC: Herbert Xu <herbert@gondor.apana.org.au>
CC: "David S. Miller" <davem@davemloft.net>
CC: Michael Roth <michael.roth@amd.com>
CC: Luis Chamberlain <mcgrof@kernel.org>
CC: Russ Weight <russ.weight@linux.dev>
CC: Danilo Krummrich <dakr@redhat.com>
CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CC: "Rafael J. Wysocki" <rafael@kernel.org>
CC: Tianfei zhang <tianfei.zhang@intel.com>
CC: Alexey Kardashevskiy <aik@amd.com>
Signed-off-by: Dionna Glaze <dionnaglaze@google.com>
---
arch/x86/kvm/svm/sev.c | 74 ++++++++++++------------------------------
1 file changed, 20 insertions(+), 54 deletions(-)
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index cea41b8cdabe4..d7cef84750b33 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -89,7 +89,7 @@ static unsigned int nr_asids;
static unsigned long *sev_asid_bitmap;
static unsigned long *sev_reclaim_asid_bitmap;
-static int snp_decommission_context(struct kvm *kvm);
+static int kvm_decommission_snp_context(struct kvm *kvm);
struct enc_region {
struct list_head list;
@@ -2168,51 +2168,12 @@ int sev_dev_get_attr(u32 group, u64 attr, u64 *val)
}
}
-/*
- * The guest context contains all the information, keys and metadata
- * associated with the guest that the firmware tracks to implement SEV
- * and SNP features. The firmware stores the guest context in hypervisor
- * provide page via the SNP_GCTX_CREATE command.
- */
-static void *snp_context_create(struct kvm *kvm, struct kvm_sev_cmd *argp)
-{
- struct sev_data_snp_addr data = {};
- void *context;
- int rc;
-
- /* Allocate memory for context page */
- context = snp_alloc_firmware_page(GFP_KERNEL_ACCOUNT);
- if (!context)
- return ERR_PTR(-ENOMEM);
-
- data.address = __psp_pa(context);
- rc = __sev_issue_cmd(argp->sev_fd, SEV_CMD_SNP_GCTX_CREATE, &data, &argp->error);
- if (rc) {
- pr_warn("Failed to create SEV-SNP context, rc %d fw_error %d",
- rc, argp->error);
- snp_free_firmware_page(context);
- return ERR_PTR(rc);
- }
-
- return context;
-}
-
-static int snp_bind_asid(struct kvm *kvm, int *error)
-{
- struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
- struct sev_data_snp_activate data = {0};
-
- data.gctx_paddr = __psp_pa(sev->snp_context);
- data.asid = sev_get_asid(kvm);
- return sev_issue_cmd(kvm, SEV_CMD_SNP_ACTIVATE, &data, error);
-}
-
static int snp_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp)
{
struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
struct sev_data_snp_launch_start start = {0};
struct kvm_sev_snp_launch_start params;
- int rc;
+ int rc, asid;
if (!sev_snp_guest(kvm))
return -ENOTTY;
@@ -2238,14 +2199,19 @@ static int snp_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp)
if (params.policy & SNP_POLICY_MASK_SINGLE_SOCKET)
return -EINVAL;
- sev->snp_context = snp_context_create(kvm, argp);
+ rc = sev_check_external_user(argp->sev_fd);
+ if (rc)
+ return rc;
+
+ asid = sev_get_asid(kvm);
+ sev->snp_context = sev_snp_create_context(asid, &argp->error);
if (IS_ERR(sev->snp_context))
return PTR_ERR(sev->snp_context);
start.gctx_paddr = __psp_pa(sev->snp_context);
start.policy = params.policy;
memcpy(start.gosvw, params.gosvw, sizeof(params.gosvw));
- rc = __sev_issue_cmd(argp->sev_fd, SEV_CMD_SNP_LAUNCH_START, &start, &argp->error);
+ rc = sev_do_cmd(SEV_CMD_SNP_LAUNCH_START, &start, &argp->error);
if (rc) {
pr_debug("%s: SEV_CMD_SNP_LAUNCH_START firmware command failed, rc %d\n",
__func__, rc);
@@ -2253,7 +2219,7 @@ static int snp_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp)
}
sev->fd = argp->sev_fd;
- rc = snp_bind_asid(kvm, &argp->error);
+ rc = sev_snp_activate_asid(asid, &argp->error);
if (rc) {
pr_debug("%s: Failed to bind ASID to SEV-SNP context, rc %d\n",
__func__, rc);
@@ -2263,7 +2229,7 @@ static int snp_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp)
return 0;
e_free_context:
- snp_decommission_context(kvm);
+ kvm_decommission_snp_context(kvm);
return rc;
}
@@ -2874,26 +2840,26 @@ int sev_vm_copy_enc_context_from(struct kvm *kvm, unsigned int source_fd)
return ret;
}
-static int snp_decommission_context(struct kvm *kvm)
+static int kvm_decommission_snp_context(struct kvm *kvm)
{
struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
- struct sev_data_snp_addr data = {};
- int ret;
+ int ret, error;
/* If context is not created then do nothing */
if (!sev->snp_context)
return 0;
- /* Do the decommision, which will unbind the ASID from the SNP context */
- data.address = __sme_pa(sev->snp_context);
+ /*
+ * Do the decommision, which will unbind the ASID from the SNP context
+ * and free the context page.
+ */
down_write(&sev_deactivate_lock);
- ret = sev_do_cmd(SEV_CMD_SNP_DECOMMISSION, &data, NULL);
+ ret = sev_snp_guest_decommission(sev->asid, &error);
up_write(&sev_deactivate_lock);
- if (WARN_ONCE(ret, "Failed to release guest context, ret %d", ret))
+ if (WARN_ONCE(ret, "Failed to release guest context, ret %d fw err %d", ret, error))
return ret;
- snp_free_firmware_page(sev->snp_context);
sev->snp_context = NULL;
return 0;
@@ -2947,7 +2913,7 @@ void sev_vm_destroy(struct kvm *kvm)
* Decomission handles unbinding of the ASID. If it fails for
* some unexpected reason, just leak the ASID.
*/
- if (snp_decommission_context(kvm))
+ if (kvm_decommission_snp_context(kvm))
return;
} else {
sev_unbind_asid(kvm, sev->handle);
--
2.47.0.277.g8800431eea-googOn 11/7/24 17:24, Dionna Glaze wrote:
> Guest context pages should be near 1-to-1 with allocated ASIDs. With the
> GCTX API, the ccp driver is better able to associate guest context pages
> with the ASID that is/will be bound to it.
>
> This is important to the firmware hotloading implementation to not
> corrupt any running VM's guest context page before userspace commits a
> new firmware.
>
> CC: Sean Christopherson <seanjc@google.com>
> CC: Paolo Bonzini <pbonzini@redhat.com>
> CC: Thomas Gleixner <tglx@linutronix.de>
> CC: Ingo Molnar <mingo@redhat.com>
> CC: Borislav Petkov <bp@alien8.de>
> CC: Dave Hansen <dave.hansen@linux.intel.com>
> CC: Ashish Kalra <ashish.kalra@amd.com>
> CC: Tom Lendacky <thomas.lendacky@amd.com>
> CC: John Allen <john.allen@amd.com>
> CC: Herbert Xu <herbert@gondor.apana.org.au>
> CC: "David S. Miller" <davem@davemloft.net>
> CC: Michael Roth <michael.roth@amd.com>
> CC: Luis Chamberlain <mcgrof@kernel.org>
> CC: Russ Weight <russ.weight@linux.dev>
> CC: Danilo Krummrich <dakr@redhat.com>
> CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> CC: "Rafael J. Wysocki" <rafael@kernel.org>
> CC: Tianfei zhang <tianfei.zhang@intel.com>
> CC: Alexey Kardashevskiy <aik@amd.com>
>
> Signed-off-by: Dionna Glaze <dionnaglaze@google.com>
> ---
> arch/x86/kvm/svm/sev.c | 74 ++++++++++++------------------------------
> 1 file changed, 20 insertions(+), 54 deletions(-)
>
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index cea41b8cdabe4..d7cef84750b33 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -89,7 +89,7 @@ static unsigned int nr_asids;
> static unsigned long *sev_asid_bitmap;
> static unsigned long *sev_reclaim_asid_bitmap;
>
> -static int snp_decommission_context(struct kvm *kvm);
> +static int kvm_decommission_snp_context(struct kvm *kvm);
Why the name change? It seems like it just makes the patch a bit harder
to follow since there are two things going on.
Thanks,
Tom
>
> struct enc_region {
> struct list_head list;
> @@ -2168,51 +2168,12 @@ int sev_dev_get_attr(u32 group, u64 attr, u64 *val)
> }
> }
>
> -/*
> - * The guest context contains all the information, keys and metadata
> - * associated with the guest that the firmware tracks to implement SEV
> - * and SNP features. The firmware stores the guest context in hypervisor
> - * provide page via the SNP_GCTX_CREATE command.
> - */
> -static void *snp_context_create(struct kvm *kvm, struct kvm_sev_cmd *argp)
> -{
> - struct sev_data_snp_addr data = {};
> - void *context;
> - int rc;
> -
> - /* Allocate memory for context page */
> - context = snp_alloc_firmware_page(GFP_KERNEL_ACCOUNT);
> - if (!context)
> - return ERR_PTR(-ENOMEM);
> -
> - data.address = __psp_pa(context);
> - rc = __sev_issue_cmd(argp->sev_fd, SEV_CMD_SNP_GCTX_CREATE, &data, &argp->error);
> - if (rc) {
> - pr_warn("Failed to create SEV-SNP context, rc %d fw_error %d",
> - rc, argp->error);
> - snp_free_firmware_page(context);
> - return ERR_PTR(rc);
> - }
> -
> - return context;
> -}
> -
> -static int snp_bind_asid(struct kvm *kvm, int *error)
> -{
> - struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
> - struct sev_data_snp_activate data = {0};
> -
> - data.gctx_paddr = __psp_pa(sev->snp_context);
> - data.asid = sev_get_asid(kvm);
> - return sev_issue_cmd(kvm, SEV_CMD_SNP_ACTIVATE, &data, error);
> -}
> -
> static int snp_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp)
> {
> struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
> struct sev_data_snp_launch_start start = {0};
> struct kvm_sev_snp_launch_start params;
> - int rc;
> + int rc, asid;
>
> if (!sev_snp_guest(kvm))
> return -ENOTTY;
> @@ -2238,14 +2199,19 @@ static int snp_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp)
> if (params.policy & SNP_POLICY_MASK_SINGLE_SOCKET)
> return -EINVAL;
>
> - sev->snp_context = snp_context_create(kvm, argp);
> + rc = sev_check_external_user(argp->sev_fd);
> + if (rc)
> + return rc;
> +
> + asid = sev_get_asid(kvm);
> + sev->snp_context = sev_snp_create_context(asid, &argp->error);
> if (IS_ERR(sev->snp_context))
> return PTR_ERR(sev->snp_context);
>
> start.gctx_paddr = __psp_pa(sev->snp_context);
> start.policy = params.policy;
> memcpy(start.gosvw, params.gosvw, sizeof(params.gosvw));
> - rc = __sev_issue_cmd(argp->sev_fd, SEV_CMD_SNP_LAUNCH_START, &start, &argp->error);
> + rc = sev_do_cmd(SEV_CMD_SNP_LAUNCH_START, &start, &argp->error);
> if (rc) {
> pr_debug("%s: SEV_CMD_SNP_LAUNCH_START firmware command failed, rc %d\n",
> __func__, rc);
> @@ -2253,7 +2219,7 @@ static int snp_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp)
> }
>
> sev->fd = argp->sev_fd;
> - rc = snp_bind_asid(kvm, &argp->error);
> + rc = sev_snp_activate_asid(asid, &argp->error);
> if (rc) {
> pr_debug("%s: Failed to bind ASID to SEV-SNP context, rc %d\n",
> __func__, rc);
> @@ -2263,7 +2229,7 @@ static int snp_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp)
> return 0;
>
> e_free_context:
> - snp_decommission_context(kvm);
> + kvm_decommission_snp_context(kvm);
>
> return rc;
> }
> @@ -2874,26 +2840,26 @@ int sev_vm_copy_enc_context_from(struct kvm *kvm, unsigned int source_fd)
> return ret;
> }
>
> -static int snp_decommission_context(struct kvm *kvm)
> +static int kvm_decommission_snp_context(struct kvm *kvm)
> {
> struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
> - struct sev_data_snp_addr data = {};
> - int ret;
> + int ret, error;
>
> /* If context is not created then do nothing */
> if (!sev->snp_context)
> return 0;
>
> - /* Do the decommision, which will unbind the ASID from the SNP context */
> - data.address = __sme_pa(sev->snp_context);
> + /*
> + * Do the decommision, which will unbind the ASID from the SNP context
> + * and free the context page.
> + */
> down_write(&sev_deactivate_lock);
> - ret = sev_do_cmd(SEV_CMD_SNP_DECOMMISSION, &data, NULL);
> + ret = sev_snp_guest_decommission(sev->asid, &error);
> up_write(&sev_deactivate_lock);
>
> - if (WARN_ONCE(ret, "Failed to release guest context, ret %d", ret))
> + if (WARN_ONCE(ret, "Failed to release guest context, ret %d fw err %d", ret, error))
> return ret;
>
> - snp_free_firmware_page(sev->snp_context);
> sev->snp_context = NULL;
>
> return 0;
> @@ -2947,7 +2913,7 @@ void sev_vm_destroy(struct kvm *kvm)
> * Decomission handles unbinding of the ASID. If it fails for
> * some unexpected reason, just leak the ASID.
> */
> - if (snp_decommission_context(kvm))
> + if (kvm_decommission_snp_context(kvm))
> return;
> } else {
> sev_unbind_asid(kvm, sev->handle);
> > diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c > > index cea41b8cdabe4..d7cef84750b33 100644 > > --- a/arch/x86/kvm/svm/sev.c > > +++ b/arch/x86/kvm/svm/sev.c > > @@ -89,7 +89,7 @@ static unsigned int nr_asids; > > static unsigned long *sev_asid_bitmap; > > static unsigned long *sev_reclaim_asid_bitmap; > > > > -static int snp_decommission_context(struct kvm *kvm); > > +static int kvm_decommission_snp_context(struct kvm *kvm); > > Why the name change? It seems like it just makes the patch a bit harder > to follow since there are two things going on. > KVM and ccp both seem to like to name their functions starting with sev_ or snp_, and it's particularly hard to determine provenance. snp_decommision_context and sev_snp_guest_decommission... which is from where? It's weird to me. > Thanks, > Tom > -- -Dionna Glaze, PhD, CISSP, CCSP (she/her)
On 11/12/24 13:33, Dionna Amalie Glaze wrote: >>> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c >>> index cea41b8cdabe4..d7cef84750b33 100644 >>> --- a/arch/x86/kvm/svm/sev.c >>> +++ b/arch/x86/kvm/svm/sev.c >>> @@ -89,7 +89,7 @@ static unsigned int nr_asids; >>> static unsigned long *sev_asid_bitmap; >>> static unsigned long *sev_reclaim_asid_bitmap; >>> >>> -static int snp_decommission_context(struct kvm *kvm); >>> +static int kvm_decommission_snp_context(struct kvm *kvm); >> >> Why the name change? It seems like it just makes the patch a bit harder >> to follow since there are two things going on. >> > > KVM and ccp both seem to like to name their functions starting with > sev_ or snp_, and it's particularly hard to determine provenance. > > snp_decommision_context and sev_snp_guest_decommission... which is > from where? It's weird to me. I guess I don't see the problem, a quick git grep -w of the name will show you where each is. Its a static function in the file, so if anything just changing/shortening the name to decommission_snp_context() would be better (especially since nothing in the svm directory should have a name that starts with kvm_). Thanks, Tom > >> Thanks, >> Tom >> > >
On Tue, Nov 12, 2024, Tom Lendacky wrote: > On 11/12/24 13:33, Dionna Amalie Glaze wrote: > >>> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c > >>> index cea41b8cdabe4..d7cef84750b33 100644 > >>> --- a/arch/x86/kvm/svm/sev.c > >>> +++ b/arch/x86/kvm/svm/sev.c > >>> @@ -89,7 +89,7 @@ static unsigned int nr_asids; > >>> static unsigned long *sev_asid_bitmap; > >>> static unsigned long *sev_reclaim_asid_bitmap; > >>> > >>> -static int snp_decommission_context(struct kvm *kvm); > >>> +static int kvm_decommission_snp_context(struct kvm *kvm); > >> > >> Why the name change? It seems like it just makes the patch a bit harder > >> to follow since there are two things going on. > >> > > > > KVM and ccp both seem to like to name their functions starting with > > sev_ or snp_, and it's particularly hard to determine provenance. > > > > snp_decommision_context and sev_snp_guest_decommission... which is > > from where? It's weird to me. > > I guess I don't see the problem, a quick git grep -w of the name will > show you where each is. Its a static function in the file, so if > anything just changing/shortening the name to decommission_snp_context() Eh, that creates just as many problems as it solves, because it mucks up the namespace and leads to discontinuity between the decommission helper and things like snp_launch_update_vmsa() and snp_launch_finish(). I agree that there isn't a strong need to fixup static symbols. That said, I do think drivers/crypto/ccp/sev-dev.c in particular needs a different namespace, and needs to use it consistently, to make it somewhat obvious that it's (almost) all about the PSP/ASP. But IMO, an even bigger mess in that area is the lack of consistency in the APIs themselves. E.g. this code where KVM uses sev_do_cmd() directly for SNP, but bounces through a wrapper for !SNP. Eww. wbinvd_on_all_cpus(); if (sev_snp_enabled) ret = sev_do_cmd(SEV_CMD_SNP_DF_FLUSH, NULL, &error); else ret = sev_guest_df_flush(&error); up_write(&sev_deactivate_lock); And then KVM has snp_page_reclaim(), but the PSP/ASP driver has snp_reclaim_pages(). So if we want to start renaming things, I vote to go a step further and clean up the APIs, e.g. with a goal of eliminating sev_do_cmd(), and possibly of making the majority of the PSP-defined structures in include/linux/psp-sev.h "private" to the PSP/ASP driver. > would be better (especially since nothing in the svm directory should > have a name that starts with kvm_). +1 to not using "kvm_". KVM often uses "kvm_" to differentiate globally visible symbols from local (static) symbols. I.e. prepending "kvm_" just trades one confusing name for another.
© 2016 - 2024 Red Hat, Inc.