* [PATCH v3 0/2] Clean the policy manipulation path in domain creation
@ 2024-05-23 9:41 Alejandro Vallejo
2024-05-23 9:41 ` [PATCH v3 1/2] tools/xg: Streamline cpu policy serialise/deserialise calls Alejandro Vallejo
2024-05-23 9:41 ` [PATCH v3 2/2] tools/xg: Clean up xend-style overrides for CPU policies Alejandro Vallejo
0 siblings, 2 replies; 8+ messages in thread
From: Alejandro Vallejo @ 2024-05-23 9:41 UTC (permalink / raw)
To: Xen-devel
Cc: Alejandro Vallejo, Anthony PERARD, Juergen Gross, Jan Beulich,
Andrew Cooper, Roger Pau Monné
v2 -> v3:
* Style adjustments
* Revert of loop index scope refactors
v1 -> v2:
* Removed xc_cpu_policy from xenguest.h (dropped v1/patch1)
* Added accessors for xc_cpu_policy so the serialised form can be extracted.
* Modified xen-cpuid to use accessors.
==== Original cover letter ====
In the context of creating a domain, we currently issue a lot of hypercalls
redundantly while populating its CPU policy; likely a side effect of
organic growth more than anything else.
However, the worst part is not the overhead (this is a glacially cold
path), but the insane amounts of boilerplate that make it really hard to
pick apart what's going on. One major contributor to this situation is the
fact that what's effectively "setup" and "teardown" phases in policy
manipulation are not factored out from the functions that perform said
manipulations, leading to the same getters and setter being invoked many
times, when once each would do.
Another big contributor is the code being unaware of when a policy is
serialised and when it's not.
This patch attempts to alleviate this situation, yielding over 200 LoC
reduction.
Patch 1: Mechanical change. Makes xc_cpu_policy_t public so it's usable
from clients of libxc/libxg.
Patch 2: Changes the (de)serialization wrappers in xenguest so they always
serialise to/from the internal buffers of xc_cpu_policy_t. The
struct is suitably expanded to hold extra information required.
Patch 3: Performs the refactor of the policy manipulation code so that it
follows a strict: PULL_POLICIES, MUTATE_POLICY (n times), PUSH_POLICY.
Subject: [PATCH v3 0/2] *** SUBJECT HERE ***
*** BLURB HERE ***
Alejandro Vallejo (2):
tools/xg: Streamline cpu policy serialise/deserialise calls
tools/xg: Clean up xend-style overrides for CPU policies
tools/include/xenguest.h | 8 +-
tools/libs/guest/xg_cpuid_x86.c | 530 ++++++++++------------------
tools/libs/guest/xg_private.h | 2 +
tools/libs/guest/xg_sr_common_x86.c | 56 ++-
tools/misc/xen-cpuid.c | 41 +--
5 files changed, 234 insertions(+), 403 deletions(-)
--
2.34.1
^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH v3 1/2] tools/xg: Streamline cpu policy serialise/deserialise calls
2024-05-23 9:41 [PATCH v3 0/2] Clean the policy manipulation path in domain creation Alejandro Vallejo
@ 2024-05-23 9:41 ` Alejandro Vallejo
2024-05-23 10:21 ` Roger Pau Monné
2024-05-23 9:41 ` [PATCH v3 2/2] tools/xg: Clean up xend-style overrides for CPU policies Alejandro Vallejo
1 sibling, 1 reply; 8+ messages in thread
From: Alejandro Vallejo @ 2024-05-23 9:41 UTC (permalink / raw)
To: Xen-devel
Cc: Alejandro Vallejo, Anthony PERARD, Juergen Gross, Jan Beulich,
Andrew Cooper, Roger Pau Monné
The idea is to use xc_cpu_policy_t as a single object containing both the
serialised and deserialised forms of the policy. Note that we need lengths
for the arrays, as the serialised policies may be shorter than the array
capacities.
* Add the serialised lengths to the struct so we can distinguish
between length and capacity of the serialisation buffers.
* Remove explicit buffer+lengths in serialise/deserialise calls
and use the internal buffer inside xc_cpu_policy_t instead.
* Refactor everything to use the new serialisation functions.
* Remove redundant serialization calls and avoid allocating dynamic
memory aside from the policy objects in xen-cpuid. Also minor cleanup
in the policy print call sites.
No functional change intended.
Signed-off-by: Alejandro Vallejo <alejandro.vallejo@cloud.com>
---
v3:
* Better context scoping in xg_sr_common_x86.
* Can't be const because write_record() takes non-const.
* Adjusted line length of xen-cpuid's print_policy.
* Adjusted error messages in xen-cpuid's print_policy.
* Reverted removal of overscoped loop indices.
---
tools/include/xenguest.h | 8 ++-
tools/libs/guest/xg_cpuid_x86.c | 98 ++++++++++++++++++++---------
tools/libs/guest/xg_private.h | 2 +
tools/libs/guest/xg_sr_common_x86.c | 56 ++++++-----------
tools/misc/xen-cpuid.c | 41 ++++--------
5 files changed, 106 insertions(+), 99 deletions(-)
diff --git a/tools/include/xenguest.h b/tools/include/xenguest.h
index e01f494b772a..563811cd8dde 100644
--- a/tools/include/xenguest.h
+++ b/tools/include/xenguest.h
@@ -799,14 +799,16 @@ int xc_cpu_policy_set_domain(xc_interface *xch, uint32_t domid,
xc_cpu_policy_t *policy);
/* Manipulate a policy via architectural representations. */
-int xc_cpu_policy_serialise(xc_interface *xch, const xc_cpu_policy_t *policy,
- xen_cpuid_leaf_t *leaves, uint32_t *nr_leaves,
- xen_msr_entry_t *msrs, uint32_t *nr_msrs);
+int xc_cpu_policy_serialise(xc_interface *xch, xc_cpu_policy_t *policy);
int xc_cpu_policy_update_cpuid(xc_interface *xch, xc_cpu_policy_t *policy,
const xen_cpuid_leaf_t *leaves,
uint32_t nr);
int xc_cpu_policy_update_msrs(xc_interface *xch, xc_cpu_policy_t *policy,
const xen_msr_entry_t *msrs, uint32_t nr);
+int xc_cpu_policy_get_leaves(xc_interface *xch, const xc_cpu_policy_t *policy,
+ const xen_cpuid_leaf_t **leaves, uint32_t *nr);
+int xc_cpu_policy_get_msrs(xc_interface *xch, const xc_cpu_policy_t *policy,
+ const xen_msr_entry_t **msrs, uint32_t *nr);
/* Compatibility calculations. */
bool xc_cpu_policy_is_compatible(xc_interface *xch, xc_cpu_policy_t *host,
diff --git a/tools/libs/guest/xg_cpuid_x86.c b/tools/libs/guest/xg_cpuid_x86.c
index 4453178100ad..4f4b86b59470 100644
--- a/tools/libs/guest/xg_cpuid_x86.c
+++ b/tools/libs/guest/xg_cpuid_x86.c
@@ -834,14 +834,13 @@ void xc_cpu_policy_destroy(xc_cpu_policy_t *policy)
}
}
-static int deserialize_policy(xc_interface *xch, xc_cpu_policy_t *policy,
- unsigned int nr_leaves, unsigned int nr_entries)
+static int deserialize_policy(xc_interface *xch, xc_cpu_policy_t *policy)
{
uint32_t err_leaf = -1, err_subleaf = -1, err_msr = -1;
int rc;
rc = x86_cpuid_copy_from_buffer(&policy->policy, policy->leaves,
- nr_leaves, &err_leaf, &err_subleaf);
+ policy->nr_leaves, &err_leaf, &err_subleaf);
if ( rc )
{
if ( err_leaf != -1 )
@@ -851,7 +850,7 @@ static int deserialize_policy(xc_interface *xch, xc_cpu_policy_t *policy,
}
rc = x86_msr_copy_from_buffer(&policy->policy, policy->msrs,
- nr_entries, &err_msr);
+ policy->nr_msrs, &err_msr);
if ( rc )
{
if ( err_msr != -1 )
@@ -878,7 +877,10 @@ int xc_cpu_policy_get_system(xc_interface *xch, unsigned int policy_idx,
return rc;
}
- rc = deserialize_policy(xch, policy, nr_leaves, nr_msrs);
+ policy->nr_leaves = nr_leaves;
+ policy->nr_msrs = nr_msrs;
+
+ rc = deserialize_policy(xch, policy);
if ( rc )
{
errno = -rc;
@@ -903,7 +905,10 @@ int xc_cpu_policy_get_domain(xc_interface *xch, uint32_t domid,
return rc;
}
- rc = deserialize_policy(xch, policy, nr_leaves, nr_msrs);
+ policy->nr_leaves = nr_leaves;
+ policy->nr_msrs = nr_msrs;
+
+ rc = deserialize_policy(xch, policy);
if ( rc )
{
errno = -rc;
@@ -917,17 +922,14 @@ int xc_cpu_policy_set_domain(xc_interface *xch, uint32_t domid,
xc_cpu_policy_t *policy)
{
uint32_t err_leaf = -1, err_subleaf = -1, err_msr = -1;
- unsigned int nr_leaves = ARRAY_SIZE(policy->leaves);
- unsigned int nr_msrs = ARRAY_SIZE(policy->msrs);
int rc;
- rc = xc_cpu_policy_serialise(xch, policy, policy->leaves, &nr_leaves,
- policy->msrs, &nr_msrs);
+ rc = xc_cpu_policy_serialise(xch, policy);
if ( rc )
return rc;
- rc = xc_set_domain_cpu_policy(xch, domid, nr_leaves, policy->leaves,
- nr_msrs, policy->msrs,
+ rc = xc_set_domain_cpu_policy(xch, domid, policy->nr_leaves, policy->leaves,
+ policy->nr_msrs, policy->msrs,
&err_leaf, &err_subleaf, &err_msr);
if ( rc )
{
@@ -942,34 +944,32 @@ int xc_cpu_policy_set_domain(xc_interface *xch, uint32_t domid,
return rc;
}
-int xc_cpu_policy_serialise(xc_interface *xch, const xc_cpu_policy_t *p,
- xen_cpuid_leaf_t *leaves, uint32_t *nr_leaves,
- xen_msr_entry_t *msrs, uint32_t *nr_msrs)
+int xc_cpu_policy_serialise(xc_interface *xch, xc_cpu_policy_t *p)
{
+ unsigned int nr_leaves = ARRAY_SIZE(p->leaves);
+ unsigned int nr_msrs = ARRAY_SIZE(p->msrs);
int rc;
- if ( leaves )
+ rc = x86_cpuid_copy_to_buffer(&p->policy, p->leaves, &nr_leaves);
+ if ( rc )
{
- rc = x86_cpuid_copy_to_buffer(&p->policy, leaves, nr_leaves);
- if ( rc )
- {
- ERROR("Failed to serialize CPUID policy");
- errno = -rc;
- return -1;
- }
+ ERROR("Failed to serialize CPUID policy");
+ errno = -rc;
+ return -1;
}
- if ( msrs )
+ p->nr_leaves = nr_leaves;
+
+ rc = x86_msr_copy_to_buffer(&p->policy, p->msrs, &nr_msrs);
+ if ( rc )
{
- rc = x86_msr_copy_to_buffer(&p->policy, msrs, nr_msrs);
- if ( rc )
- {
- ERROR("Failed to serialize MSR policy");
- errno = -rc;
- return -1;
- }
+ ERROR("Failed to serialize MSR policy");
+ errno = -rc;
+ return -1;
}
+ p->nr_msrs = nr_msrs;
+
errno = 0;
return 0;
}
@@ -1012,6 +1012,42 @@ int xc_cpu_policy_update_msrs(xc_interface *xch, xc_cpu_policy_t *policy,
return rc;
}
+int xc_cpu_policy_get_leaves(xc_interface *xch,
+ const xc_cpu_policy_t *policy,
+ const xen_cpuid_leaf_t **leaves,
+ uint32_t *nr)
+{
+ if ( !policy )
+ {
+ ERROR("Failed to fetch CPUID leaves from policy object");
+ errno = -EINVAL;
+ return -1;
+ }
+
+ *leaves = policy->leaves;
+ *nr = policy->nr_leaves;
+
+ return 0;
+}
+
+int xc_cpu_policy_get_msrs(xc_interface *xch,
+ const xc_cpu_policy_t *policy,
+ const xen_msr_entry_t **msrs,
+ uint32_t *nr)
+{
+ if ( !policy )
+ {
+ ERROR("Failed to fetch MSRs from policy object");
+ errno = -EINVAL;
+ return -1;
+ }
+
+ *msrs = policy->msrs;
+ *nr = policy->nr_msrs;
+
+ return 0;
+}
+
bool xc_cpu_policy_is_compatible(xc_interface *xch, xc_cpu_policy_t *host,
xc_cpu_policy_t *guest)
{
diff --git a/tools/libs/guest/xg_private.h b/tools/libs/guest/xg_private.h
index d73947094f2e..a65dae818f3d 100644
--- a/tools/libs/guest/xg_private.h
+++ b/tools/libs/guest/xg_private.h
@@ -177,6 +177,8 @@ struct xc_cpu_policy {
struct cpu_policy policy;
xen_cpuid_leaf_t leaves[CPUID_MAX_SERIALISED_LEAVES];
xen_msr_entry_t msrs[MSR_MAX_SERIALISED_ENTRIES];
+ uint32_t nr_leaves;
+ uint32_t nr_msrs;
};
#endif /* x86 */
diff --git a/tools/libs/guest/xg_sr_common_x86.c b/tools/libs/guest/xg_sr_common_x86.c
index 563b4f016877..a0d67c3211c6 100644
--- a/tools/libs/guest/xg_sr_common_x86.c
+++ b/tools/libs/guest/xg_sr_common_x86.c
@@ -1,4 +1,5 @@
#include "xg_sr_common_x86.h"
+#include "xg_sr_stream_format.h"
int write_x86_tsc_info(struct xc_sr_context *ctx)
{
@@ -45,54 +46,39 @@ int handle_x86_tsc_info(struct xc_sr_context *ctx, struct xc_sr_record *rec)
int write_x86_cpu_policy_records(struct xc_sr_context *ctx)
{
xc_interface *xch = ctx->xch;
- struct xc_sr_record cpuid = { .type = REC_TYPE_X86_CPUID_POLICY, };
- struct xc_sr_record msrs = { .type = REC_TYPE_X86_MSR_POLICY, };
- uint32_t nr_leaves = 0, nr_msrs = 0;
- xc_cpu_policy_t *policy = NULL;
+ xc_cpu_policy_t *policy = xc_cpu_policy_init();
int rc;
- if ( xc_cpu_policy_get_size(xch, &nr_leaves, &nr_msrs) < 0 )
- {
- PERROR("Unable to get CPU Policy size");
- return -1;
- }
-
- cpuid.data = malloc(nr_leaves * sizeof(xen_cpuid_leaf_t));
- msrs.data = malloc(nr_msrs * sizeof(xen_msr_entry_t));
- policy = xc_cpu_policy_init();
- if ( !cpuid.data || !msrs.data || !policy )
- {
- ERROR("Cannot allocate memory for CPU Policy");
- rc = -1;
- goto out;
- }
-
- if ( xc_cpu_policy_get_domain(xch, ctx->domid, policy) )
+ if ( !policy || xc_cpu_policy_get_domain(xch, ctx->domid, policy) )
{
PERROR("Unable to get d%d CPU Policy", ctx->domid);
rc = -1;
goto out;
}
- if ( xc_cpu_policy_serialise(xch, policy, cpuid.data, &nr_leaves,
- msrs.data, &nr_msrs) )
- {
- PERROR("Unable to serialize d%d CPU Policy", ctx->domid);
- rc = -1;
- goto out;
- }
- cpuid.length = nr_leaves * sizeof(xen_cpuid_leaf_t);
- if ( cpuid.length )
+
+ if ( policy->nr_leaves )
{
- rc = write_record(ctx, &cpuid);
+ struct xc_sr_record record = {
+ .type = REC_TYPE_X86_CPUID_POLICY,
+ .data = policy->leaves,
+ .length = policy->nr_leaves * sizeof(*policy->leaves),
+ };
+
+ rc = write_record(ctx, &record);
if ( rc )
goto out;
}
- msrs.length = nr_msrs * sizeof(xen_msr_entry_t);
- if ( msrs.length )
+ if ( policy->nr_msrs )
{
- rc = write_record(ctx, &msrs);
+ struct xc_sr_record record = {
+ .type = REC_TYPE_X86_MSR_POLICY,
+ .data = policy->msrs,
+ .length = policy->nr_msrs * sizeof(*policy->msrs),
+ };
+
+ rc = write_record(ctx, &record);
if ( rc )
goto out;
}
@@ -100,8 +86,6 @@ int write_x86_cpu_policy_records(struct xc_sr_context *ctx)
rc = 0;
out:
- free(cpuid.data);
- free(msrs.data);
xc_cpu_policy_destroy(policy);
return rc;
diff --git a/tools/misc/xen-cpuid.c b/tools/misc/xen-cpuid.c
index 4c4593528dfe..488f43378406 100644
--- a/tools/misc/xen-cpuid.c
+++ b/tools/misc/xen-cpuid.c
@@ -156,12 +156,18 @@ static void dump_info(xc_interface *xch, bool detail)
free(fs);
}
-
-static void print_policy(const char *name,
- xen_cpuid_leaf_t *leaves, uint32_t nr_leaves,
- xen_msr_entry_t *msrs, uint32_t nr_msrs)
+static void print_policy(xc_interface *xch, const char *name,
+ const xc_cpu_policy_t *policy)
{
unsigned int l;
+ const xen_cpuid_leaf_t *leaves;
+ const xen_msr_entry_t *msrs;
+ uint32_t nr_leaves, nr_msrs;
+
+ if ( xc_cpu_policy_get_leaves(xch, policy, &leaves, &nr_leaves) )
+ err(1, "xc_cpu_policy_get_leaves()");
+ if ( xc_cpu_policy_get_msrs(xch, policy, &msrs, &nr_msrs) )
+ err(1, "xc_cpu_policy_get_msrs()");
printf("%s policy: %u leaves, %u MSRs\n", name, nr_leaves, nr_msrs);
printf(" CPUID:\n");
@@ -287,8 +293,6 @@ int main(int argc, char **argv)
[ XEN_SYSCTL_cpu_policy_pv_default ] = "PV Default",
[ XEN_SYSCTL_cpu_policy_hvm_default ] = "HVM Default",
};
- xen_cpuid_leaf_t *leaves;
- xen_msr_entry_t *msrs;
uint32_t i, max_leaves, max_msrs;
xc_interface *xch = xc_interface_open(0, 0, 0);
@@ -305,36 +309,21 @@ int main(int argc, char **argv)
printf("Xen reports there are maximum %u leaves and %u MSRs\n",
max_leaves, max_msrs);
- leaves = calloc(max_leaves, sizeof(xen_cpuid_leaf_t));
- if ( !leaves )
- err(1, "calloc(max_leaves)");
- msrs = calloc(max_msrs, sizeof(xen_msr_entry_t));
- if ( !msrs )
- err(1, "calloc(max_msrs)");
-
if ( domid != -1 )
{
char name[20];
- uint32_t nr_leaves = max_leaves;
- uint32_t nr_msrs = max_msrs;
if ( xc_cpu_policy_get_domain(xch, domid, policy) )
err(1, "xc_cpu_policy_get_domain(, %d, )", domid);
- if ( xc_cpu_policy_serialise(xch, policy, leaves, &nr_leaves,
- msrs, &nr_msrs) )
- err(1, "xc_cpu_policy_serialise");
snprintf(name, sizeof(name), "Domain %d", domid);
- print_policy(name, leaves, nr_leaves, msrs, nr_msrs);
+ print_policy(xch, name, policy);
}
else
{
/* Get system policies */
for ( i = 0; i < ARRAY_SIZE(sys_policies); ++i )
{
- uint32_t nr_leaves = max_leaves;
- uint32_t nr_msrs = max_msrs;
-
if ( xc_cpu_policy_get_system(xch, i, policy) )
{
if ( errno == EOPNOTSUPP )
@@ -346,18 +335,12 @@ int main(int argc, char **argv)
err(1, "xc_cpu_policy_get_system(, %s, )", sys_policies[i]);
}
- if ( xc_cpu_policy_serialise(xch, policy, leaves, &nr_leaves,
- msrs, &nr_msrs) )
- err(1, "xc_cpu_policy_serialise");
- print_policy(sys_policies[i], leaves, nr_leaves,
- msrs, nr_msrs);
+ print_policy(xch, sys_policies[i], policy);
}
}
xc_cpu_policy_destroy(policy);
- free(leaves);
- free(msrs);
xc_interface_close(xch);
}
else if ( mode == MODE_INFO || mode == MODE_DETAIL )
--
2.34.1
^ permalink raw reply related [flat|nested] 8+ messages in thread
* [PATCH v3 2/2] tools/xg: Clean up xend-style overrides for CPU policies
2024-05-23 9:41 [PATCH v3 0/2] Clean the policy manipulation path in domain creation Alejandro Vallejo
2024-05-23 9:41 ` [PATCH v3 1/2] tools/xg: Streamline cpu policy serialise/deserialise calls Alejandro Vallejo
@ 2024-05-23 9:41 ` Alejandro Vallejo
2024-05-23 10:47 ` Roger Pau Monné
1 sibling, 1 reply; 8+ messages in thread
From: Alejandro Vallejo @ 2024-05-23 9:41 UTC (permalink / raw)
To: Xen-devel; +Cc: Alejandro Vallejo, Anthony PERARD, Juergen Gross
Factor out policy getters/setters from both (CPUID and MSR) policy override
functions. Additionally, use host policy rather than featureset when
preparing the cur policy, saving one hypercall and several lines of
boilerplate.
No functional change intended.
Signed-off-by: Alejandro Vallejo <alejandro.vallejo@cloud.com>
---
v3:
* Restored overscoped loop indices
* Split long line in conditional
---
tools/libs/guest/xg_cpuid_x86.c | 438 ++++++++++----------------------
1 file changed, 131 insertions(+), 307 deletions(-)
diff --git a/tools/libs/guest/xg_cpuid_x86.c b/tools/libs/guest/xg_cpuid_x86.c
index 4f4b86b59470..1e631fd46d2f 100644
--- a/tools/libs/guest/xg_cpuid_x86.c
+++ b/tools/libs/guest/xg_cpuid_x86.c
@@ -36,6 +36,34 @@ enum {
#define bitmaskof(idx) (1u << ((idx) & 31))
#define featureword_of(idx) ((idx) >> 5)
+static int deserialize_policy(xc_interface *xch, xc_cpu_policy_t *policy)
+{
+ uint32_t err_leaf = -1, err_subleaf = -1, err_msr = -1;
+ int rc;
+
+ rc = x86_cpuid_copy_from_buffer(&policy->policy, policy->leaves,
+ policy->nr_leaves, &err_leaf, &err_subleaf);
+ if ( rc )
+ {
+ if ( err_leaf != -1 )
+ ERROR("Failed to deserialise CPUID (err leaf %#x, subleaf %#x) (%d = %s)",
+ err_leaf, err_subleaf, -rc, strerror(-rc));
+ return rc;
+ }
+
+ rc = x86_msr_copy_from_buffer(&policy->policy, policy->msrs,
+ policy->nr_msrs, &err_msr);
+ if ( rc )
+ {
+ if ( err_msr != -1 )
+ ERROR("Failed to deserialise MSR (err MSR %#x) (%d = %s)",
+ err_msr, -rc, strerror(-rc));
+ return rc;
+ }
+
+ return 0;
+}
+
int xc_get_cpu_levelling_caps(xc_interface *xch, uint32_t *caps)
{
struct xen_sysctl sysctl = {};
@@ -260,102 +288,37 @@ static int compare_leaves(const void *l, const void *r)
return 0;
}
-static xen_cpuid_leaf_t *find_leaf(
- xen_cpuid_leaf_t *leaves, unsigned int nr_leaves,
- const struct xc_xend_cpuid *xend)
+static xen_cpuid_leaf_t *find_leaf(xc_cpu_policy_t *p,
+ const struct xc_xend_cpuid *xend)
{
const xen_cpuid_leaf_t key = { xend->leaf, xend->subleaf };
- return bsearch(&key, leaves, nr_leaves, sizeof(*leaves), compare_leaves);
+ return bsearch(&key, p->leaves, ARRAY_SIZE(p->leaves),
+ sizeof(*p->leaves), compare_leaves);
}
-static int xc_cpuid_xend_policy(
- xc_interface *xch, uint32_t domid, const struct xc_xend_cpuid *xend)
+static int xc_cpuid_xend_policy(xc_interface *xch, uint32_t domid,
+ const struct xc_xend_cpuid *xend,
+ xc_cpu_policy_t *host,
+ xc_cpu_policy_t *def,
+ xc_cpu_policy_t *cur)
{
- int rc;
- bool hvm;
- xc_domaininfo_t di;
- unsigned int nr_leaves, nr_msrs;
- uint32_t err_leaf = -1, err_subleaf = -1, err_msr = -1;
- /*
- * Three full policies. The host, default for the domain type,
- * and domain current.
- */
- xen_cpuid_leaf_t *host = NULL, *def = NULL, *cur = NULL;
- unsigned int nr_host, nr_def, nr_cur;
-
- if ( (rc = xc_domain_getinfo_single(xch, domid, &di)) < 0 )
- {
- PERROR("Failed to obtain d%d info", domid);
- rc = -errno;
- goto fail;
- }
- hvm = di.flags & XEN_DOMINF_hvm_guest;
-
- rc = xc_cpu_policy_get_size(xch, &nr_leaves, &nr_msrs);
- if ( rc )
- {
- PERROR("Failed to obtain policy info size");
- rc = -errno;
- goto fail;
- }
-
- rc = -ENOMEM;
- if ( (host = calloc(nr_leaves, sizeof(*host))) == NULL ||
- (def = calloc(nr_leaves, sizeof(*def))) == NULL ||
- (cur = calloc(nr_leaves, sizeof(*cur))) == NULL )
- {
- ERROR("Unable to allocate memory for %u CPUID leaves", nr_leaves);
- goto fail;
- }
-
- /* Get the domain's current policy. */
- nr_msrs = 0;
- nr_cur = nr_leaves;
- rc = get_domain_cpu_policy(xch, domid, &nr_cur, cur, &nr_msrs, NULL);
- if ( rc )
- {
- PERROR("Failed to obtain d%d current policy", domid);
- rc = -errno;
- goto fail;
- }
+ if ( !xend )
+ return 0;
- /* Get the domain type's default policy. */
- nr_msrs = 0;
- nr_def = nr_leaves;
- rc = get_system_cpu_policy(xch, hvm ? XEN_SYSCTL_cpu_policy_hvm_default
- : XEN_SYSCTL_cpu_policy_pv_default,
- &nr_def, def, &nr_msrs, NULL);
- if ( rc )
- {
- PERROR("Failed to obtain %s def policy", hvm ? "hvm" : "pv");
- rc = -errno;
- goto fail;
- }
+ if ( !host || !def || !cur )
+ return -EINVAL;
- /* Get the host policy. */
- nr_msrs = 0;
- nr_host = nr_leaves;
- rc = get_system_cpu_policy(xch, XEN_SYSCTL_cpu_policy_host,
- &nr_host, host, &nr_msrs, NULL);
- if ( rc )
- {
- PERROR("Failed to obtain host policy");
- rc = -errno;
- goto fail;
- }
-
- rc = -EINVAL;
for ( ; xend->leaf != XEN_CPUID_INPUT_UNUSED; ++xend )
{
- xen_cpuid_leaf_t *cur_leaf = find_leaf(cur, nr_cur, xend);
- const xen_cpuid_leaf_t *def_leaf = find_leaf(def, nr_def, xend);
- const xen_cpuid_leaf_t *host_leaf = find_leaf(host, nr_host, xend);
+ xen_cpuid_leaf_t *cur_leaf = find_leaf(cur, xend);
+ const xen_cpuid_leaf_t *def_leaf = find_leaf(def, xend);
+ const xen_cpuid_leaf_t *host_leaf = find_leaf(host, xend);
if ( cur_leaf == NULL || def_leaf == NULL || host_leaf == NULL )
{
ERROR("Missing leaf %#x, subleaf %#x", xend->leaf, xend->subleaf);
- goto fail;
+ return -EINVAL;
}
for ( unsigned int i = 0; i < ARRAY_SIZE(xend->policy); i++ )
@@ -384,7 +347,7 @@ static int xc_cpuid_xend_policy(
{
ERROR("Bad character '%c' in policy[%d] string '%s'",
xend->policy[i][j], i, xend->policy[i]);
- goto fail;
+ return -EINVAL;
}
clear_bit(31 - j, cur_reg);
@@ -394,25 +357,7 @@ static int xc_cpuid_xend_policy(
}
}
- /* Feed the transformed currrent policy back up to Xen. */
- rc = xc_set_domain_cpu_policy(xch, domid, nr_cur, cur, 0, NULL,
- &err_leaf, &err_subleaf, &err_msr);
- if ( rc )
- {
- PERROR("Failed to set d%d's policy (err leaf %#x, subleaf %#x, msr %#x)",
- domid, err_leaf, err_subleaf, err_msr);
- rc = -errno;
- goto fail;
- }
-
- /* Success! */
-
- fail:
- free(cur);
- free(def);
- free(host);
-
- return rc;
+ return 0;
}
static int compare_msr(const void *l, const void *r)
@@ -426,104 +371,38 @@ static int compare_msr(const void *l, const void *r)
return lhs->idx < rhs->idx ? -1 : 1;
}
-static xen_msr_entry_t *find_msr(
- xen_msr_entry_t *msrs, unsigned int nr_msrs,
- uint32_t index)
+static xen_msr_entry_t *find_msr(xc_cpu_policy_t *p,
+ uint32_t index)
{
const xen_msr_entry_t key = { .idx = index };
- return bsearch(&key, msrs, nr_msrs, sizeof(*msrs), compare_msr);
+ return bsearch(&key, p->msrs, ARRAY_SIZE(p->msrs),
+ sizeof(*p->msrs), compare_msr);
}
-
static int xc_msr_policy(xc_interface *xch, domid_t domid,
- const struct xc_msr *msr)
+ const struct xc_msr *msr,
+ xc_cpu_policy_t *host,
+ xc_cpu_policy_t *def,
+ xc_cpu_policy_t *cur)
{
- int rc;
- bool hvm;
- xc_domaininfo_t di;
- unsigned int nr_leaves, nr_msrs;
- uint32_t err_leaf = -1, err_subleaf = -1, err_msr = -1;
- /*
- * Three full policies. The host, default for the domain type,
- * and domain current.
- */
- xen_msr_entry_t *host = NULL, *def = NULL, *cur = NULL;
- unsigned int nr_host, nr_def, nr_cur;
-
- if ( (rc = xc_domain_getinfo_single(xch, domid, &di)) < 0 )
- {
- PERROR("Failed to obtain d%d info", domid);
- rc = -errno;
- goto out;
- }
- hvm = di.flags & XEN_DOMINF_hvm_guest;
-
- rc = xc_cpu_policy_get_size(xch, &nr_leaves, &nr_msrs);
- if ( rc )
- {
- PERROR("Failed to obtain policy info size");
- rc = -errno;
- goto out;
- }
-
- if ( (host = calloc(nr_msrs, sizeof(*host))) == NULL ||
- (def = calloc(nr_msrs, sizeof(*def))) == NULL ||
- (cur = calloc(nr_msrs, sizeof(*cur))) == NULL )
- {
- ERROR("Unable to allocate memory for %u CPUID leaves", nr_leaves);
- rc = -ENOMEM;
- goto out;
- }
-
- /* Get the domain's current policy. */
- nr_leaves = 0;
- nr_cur = nr_msrs;
- rc = get_domain_cpu_policy(xch, domid, &nr_leaves, NULL, &nr_cur, cur);
- if ( rc )
- {
- PERROR("Failed to obtain d%d current policy", domid);
- rc = -errno;
- goto out;
- }
-
- /* Get the domain type's default policy. */
- nr_leaves = 0;
- nr_def = nr_msrs;
- rc = get_system_cpu_policy(xch, hvm ? XEN_SYSCTL_cpu_policy_hvm_default
- : XEN_SYSCTL_cpu_policy_pv_default,
- &nr_leaves, NULL, &nr_def, def);
- if ( rc )
- {
- PERROR("Failed to obtain %s def policy", hvm ? "hvm" : "pv");
- rc = -errno;
- goto out;
- }
+ if ( !msr )
+ return 0;
- /* Get the host policy. */
- nr_leaves = 0;
- nr_host = nr_msrs;
- rc = get_system_cpu_policy(xch, XEN_SYSCTL_cpu_policy_host,
- &nr_leaves, NULL, &nr_host, host);
- if ( rc )
- {
- PERROR("Failed to obtain host policy");
- rc = -errno;
- goto out;
- }
+ if ( !host || !def || !cur )
+ return -EINVAL;
for ( ; msr->index != XC_MSR_INPUT_UNUSED; ++msr )
{
- xen_msr_entry_t *cur_msr = find_msr(cur, nr_cur, msr->index);
- const xen_msr_entry_t *def_msr = find_msr(def, nr_def, msr->index);
- const xen_msr_entry_t *host_msr = find_msr(host, nr_host, msr->index);
unsigned int i;
+ xen_msr_entry_t *cur_msr = find_msr(cur, msr->index);
+ const xen_msr_entry_t *def_msr = find_msr(def, msr->index);
+ const xen_msr_entry_t *host_msr = find_msr(host, msr->index);
if ( cur_msr == NULL || def_msr == NULL || host_msr == NULL )
{
ERROR("Missing MSR %#x", msr->index);
- rc = -ENOENT;
- goto out;
+ return -ENOENT;
}
for ( i = 0; i < ARRAY_SIZE(msr->policy) - 1; i++ )
@@ -542,8 +421,7 @@ static int xc_msr_policy(xc_interface *xch, domid_t domid,
{
ERROR("MSR index %#x: bad character '%c' in policy string '%s'",
msr->index, msr->policy[i], msr->policy);
- rc = -EINVAL;
- goto out;
+ return -EINVAL;
}
if ( val )
@@ -553,25 +431,7 @@ static int xc_msr_policy(xc_interface *xch, domid_t domid,
}
}
- /* Feed the transformed policy back up to Xen. */
- rc = xc_set_domain_cpu_policy(xch, domid, 0, NULL, nr_cur, cur,
- &err_leaf, &err_subleaf, &err_msr);
- if ( rc )
- {
- PERROR("Failed to set d%d's policy (err leaf %#x, subleaf %#x, msr %#x)",
- domid, err_leaf, err_subleaf, err_msr);
- rc = -errno;
- goto out;
- }
-
- /* Success! */
-
- out:
- free(cur);
- free(def);
- free(host);
-
- return rc;
+ return 0;
}
int xc_cpuid_apply_policy(xc_interface *xch, uint32_t domid, bool restore,
@@ -583,14 +443,17 @@ int xc_cpuid_apply_policy(xc_interface *xch, uint32_t domid, bool restore,
int rc;
bool hvm;
xc_domaininfo_t di;
- struct xc_cpu_policy *p = xc_cpu_policy_init();
- unsigned int i, nr_leaves = ARRAY_SIZE(p->leaves), nr_msrs = 0;
- uint32_t err_leaf = -1, err_subleaf = -1, err_msr = -1;
- uint32_t host_featureset[FEATURESET_NR_ENTRIES] = {};
- uint32_t len = ARRAY_SIZE(host_featureset);
+ unsigned int i;
- if ( !p )
- return -ENOMEM;
+ struct xc_cpu_policy *host = xc_cpu_policy_init();
+ struct xc_cpu_policy *def = xc_cpu_policy_init();
+ struct xc_cpu_policy *cur = xc_cpu_policy_init();
+
+ if ( !host || !def || !cur )
+ {
+ rc = -ENOMEM;
+ goto out;
+ }
if ( (rc = xc_domain_getinfo_single(xch, domid, &di)) < 0 )
{
@@ -600,21 +463,19 @@ int xc_cpuid_apply_policy(xc_interface *xch, uint32_t domid, bool restore,
}
hvm = di.flags & XEN_DOMINF_hvm_guest;
- /* Get the host policy. */
- rc = xc_get_cpu_featureset(xch, XEN_SYSCTL_cpu_featureset_host,
- &len, host_featureset);
- /* Tolerate "buffer too small", as we've got the bits we need. */
- if ( rc && errno != ENOBUFS )
+ /* Get the raw host policy */
+ rc = xc_cpu_policy_get_system(xch, XEN_SYSCTL_cpu_policy_host, host);
+ if ( rc )
{
- PERROR("Failed to obtain host featureset");
+ PERROR("Failed to obtain host policy");
rc = -errno;
goto out;
}
/* Get the domain's default policy. */
- rc = get_system_cpu_policy(xch, hvm ? XEN_SYSCTL_cpu_policy_hvm_default
- : XEN_SYSCTL_cpu_policy_pv_default,
- &nr_leaves, p->leaves, &nr_msrs, NULL);
+ rc = xc_cpu_policy_get_system(xch, hvm ? XEN_SYSCTL_cpu_policy_hvm_default
+ : XEN_SYSCTL_cpu_policy_pv_default,
+ def);
if ( rc )
{
PERROR("Failed to obtain %s default policy", hvm ? "hvm" : "pv");
@@ -622,14 +483,8 @@ int xc_cpuid_apply_policy(xc_interface *xch, uint32_t domid, bool restore,
goto out;
}
- rc = x86_cpuid_copy_from_buffer(&p->policy, p->leaves, nr_leaves,
- &err_leaf, &err_subleaf);
- if ( rc )
- {
- ERROR("Failed to deserialise CPUID (err leaf %#x, subleaf %#x) (%d = %s)",
- err_leaf, err_subleaf, -rc, strerror(-rc));
- goto out;
- }
+ /* Copy the deserialised default policy to modify it */
+ memcpy(cur, def, sizeof(*cur));
if ( restore )
{
@@ -647,18 +502,18 @@ int xc_cpuid_apply_policy(xc_interface *xch, uint32_t domid, bool restore,
* - Re-enable features which have become (possibly) off by default.
*/
- p->policy.basic.rdrand = test_bit(X86_FEATURE_RDRAND, host_featureset);
- p->policy.feat.hle = test_bit(X86_FEATURE_HLE, host_featureset);
- p->policy.feat.rtm = test_bit(X86_FEATURE_RTM, host_featureset);
+ cur->policy.basic.rdrand = host->policy.basic.rdrand;
+ cur->policy.feat.hle = host->policy.feat.hle;
+ cur->policy.feat.rtm = host->policy.feat.rtm;
if ( hvm )
{
- p->policy.feat.mpx = test_bit(X86_FEATURE_MPX, host_featureset);
+ cur->policy.feat.mpx = host->policy.feat.mpx;
}
- p->policy.basic.max_leaf = min(p->policy.basic.max_leaf, 0xdu);
- p->policy.feat.max_subleaf = 0;
- p->policy.extd.max_leaf = min(p->policy.extd.max_leaf, 0x8000001c);
+ cur->policy.basic.max_leaf = min(cur->policy.basic.max_leaf, 0xdu);
+ cur->policy.feat.max_subleaf = 0;
+ cur->policy.extd.max_leaf = min(cur->policy.extd.max_leaf, 0x8000001c);
}
if ( featureset )
@@ -702,17 +557,17 @@ int xc_cpuid_apply_policy(xc_interface *xch, uint32_t domid, bool restore,
}
}
- x86_cpu_featureset_to_policy(feat, &p->policy);
+ x86_cpu_featureset_to_policy(feat, &cur->policy);
}
else
{
- p->policy.extd.itsc = itsc;
+ cur->policy.extd.itsc = itsc;
if ( hvm )
{
- p->policy.basic.pae = pae;
- p->policy.basic.vmx = nested_virt;
- p->policy.extd.svm = nested_virt;
+ cur->policy.basic.pae = pae;
+ cur->policy.basic.vmx = nested_virt;
+ cur->policy.extd.svm = nested_virt;
}
}
@@ -722,8 +577,8 @@ int xc_cpuid_apply_policy(xc_interface *xch, uint32_t domid, bool restore,
* On hardware without CPUID Faulting, PV guests see real topology.
* As a consequence, they also need to see the host htt/cmp fields.
*/
- p->policy.basic.htt = test_bit(X86_FEATURE_HTT, host_featureset);
- p->policy.extd.cmp_legacy = test_bit(X86_FEATURE_CMP_LEGACY, host_featureset);
+ cur->policy.basic.htt = host->policy.basic.htt;
+ cur->policy.extd.cmp_legacy = host->policy.extd.cmp_legacy;
}
else
{
@@ -731,28 +586,28 @@ int xc_cpuid_apply_policy(xc_interface *xch, uint32_t domid, bool restore,
* Topology for HVM guests is entirely controlled by Xen. For now, we
* hardcode APIC_ID = vcpu_id * 2 to give the illusion of no SMT.
*/
- p->policy.basic.htt = true;
- p->policy.extd.cmp_legacy = false;
+ cur->policy.basic.htt = true;
+ cur->policy.extd.cmp_legacy = false;
/*
* Leaf 1 EBX[23:16] is Maximum Logical Processors Per Package.
* Update to reflect vLAPIC_ID = vCPU_ID * 2, but make sure to avoid
* overflow.
*/
- if ( !p->policy.basic.lppp )
- p->policy.basic.lppp = 2;
- else if ( !(p->policy.basic.lppp & 0x80) )
- p->policy.basic.lppp *= 2;
+ if ( !cur->policy.basic.lppp )
+ cur->policy.basic.lppp = 2;
+ else if ( !(cur->policy.basic.lppp & 0x80) )
+ cur->policy.basic.lppp *= 2;
- switch ( p->policy.x86_vendor )
+ switch ( cur->policy.x86_vendor )
{
case X86_VENDOR_INTEL:
- for ( i = 0; (p->policy.cache.subleaf[i].type &&
- i < ARRAY_SIZE(p->policy.cache.raw)); ++i )
+ for ( i = 0; (cur->policy.cache.subleaf[i].type &&
+ i < ARRAY_SIZE(cur->policy.cache.raw)); ++i )
{
- p->policy.cache.subleaf[i].cores_per_package =
- (p->policy.cache.subleaf[i].cores_per_package << 1) | 1;
- p->policy.cache.subleaf[i].threads_per_cache = 0;
+ cur->policy.cache.subleaf[i].cores_per_package =
+ (cur->policy.cache.subleaf[i].cores_per_package << 1) | 1;
+ cur->policy.cache.subleaf[i].threads_per_cache = 0;
}
break;
@@ -772,49 +627,46 @@ int xc_cpuid_apply_policy(xc_interface *xch, uint32_t domid, bool restore,
* apic_id_size values greater than 7. Limit the value to
* 7 for now.
*/
- if ( p->policy.extd.nc < 0x7f )
+ if ( cur->policy.extd.nc < 0x7f )
{
- if ( p->policy.extd.apic_id_size != 0 && p->policy.extd.apic_id_size < 0x7 )
- p->policy.extd.apic_id_size++;
+ if ( cur->policy.extd.apic_id_size != 0 &&
+ cur->policy.extd.apic_id_size < 0x7 )
+ cur->policy.extd.apic_id_size++;
- p->policy.extd.nc = (p->policy.extd.nc << 1) | 1;
+ cur->policy.extd.nc = (cur->policy.extd.nc << 1) | 1;
}
break;
}
}
- nr_leaves = ARRAY_SIZE(p->leaves);
- rc = x86_cpuid_copy_to_buffer(&p->policy, p->leaves, &nr_leaves);
- if ( rc )
+ if ( xend || msr )
{
- ERROR("Failed to serialise CPUID (%d = %s)", -rc, strerror(-rc));
- goto out;
+ /* The overrides are over the serialised form of the policy */
+ if ( (rc = xc_cpu_policy_serialise(xch, cur)) )
+ goto out;
+
+ if ( (rc = xc_cpuid_xend_policy(xch, domid, xend, host, def, cur)) )
+ goto out;
+ if ( (rc = xc_msr_policy(xch, domid, msr, host, def, cur)) )
+ goto out;
+
+ if ( (rc = deserialize_policy(xch, cur)) )
+ goto out;
}
- rc = xc_set_domain_cpu_policy(xch, domid, nr_leaves, p->leaves, 0, NULL,
- &err_leaf, &err_subleaf, &err_msr);
+ rc = xc_cpu_policy_set_domain(xch, domid, cur);
if ( rc )
{
- PERROR("Failed to set d%d's policy (err leaf %#x, subleaf %#x, msr %#x)",
- domid, err_leaf, err_subleaf, err_msr);
rc = -errno;
goto out;
}
- if ( xend && (rc = xc_cpuid_xend_policy(xch, domid, xend)) )
- goto out;
-
- if ( msr )
- {
- rc = xc_msr_policy(xch, domid, msr);
- if ( rc )
- goto out;
- }
-
rc = 0;
out:
- xc_cpu_policy_destroy(p);
+ xc_cpu_policy_destroy(def);
+ xc_cpu_policy_destroy(host);
+ xc_cpu_policy_destroy(cur);
return rc;
}
@@ -834,34 +686,6 @@ void xc_cpu_policy_destroy(xc_cpu_policy_t *policy)
}
}
-static int deserialize_policy(xc_interface *xch, xc_cpu_policy_t *policy)
-{
- uint32_t err_leaf = -1, err_subleaf = -1, err_msr = -1;
- int rc;
-
- rc = x86_cpuid_copy_from_buffer(&policy->policy, policy->leaves,
- policy->nr_leaves, &err_leaf, &err_subleaf);
- if ( rc )
- {
- if ( err_leaf != -1 )
- ERROR("Failed to deserialise CPUID (err leaf %#x, subleaf %#x) (%d = %s)",
- err_leaf, err_subleaf, -rc, strerror(-rc));
- return rc;
- }
-
- rc = x86_msr_copy_from_buffer(&policy->policy, policy->msrs,
- policy->nr_msrs, &err_msr);
- if ( rc )
- {
- if ( err_msr != -1 )
- ERROR("Failed to deserialise MSR (err MSR %#x) (%d = %s)",
- err_msr, -rc, strerror(-rc));
- return rc;
- }
-
- return 0;
-}
-
int xc_cpu_policy_get_system(xc_interface *xch, unsigned int policy_idx,
xc_cpu_policy_t *policy)
{
--
2.34.1
^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH v3 1/2] tools/xg: Streamline cpu policy serialise/deserialise calls
2024-05-23 9:41 ` [PATCH v3 1/2] tools/xg: Streamline cpu policy serialise/deserialise calls Alejandro Vallejo
@ 2024-05-23 10:21 ` Roger Pau Monné
2024-05-24 10:32 ` Alejandro Vallejo
0 siblings, 1 reply; 8+ messages in thread
From: Roger Pau Monné @ 2024-05-23 10:21 UTC (permalink / raw)
To: Alejandro Vallejo
Cc: Xen-devel, Anthony PERARD, Juergen Gross, Jan Beulich,
Andrew Cooper
On Thu, May 23, 2024 at 10:41:29AM +0100, Alejandro Vallejo wrote:
> The idea is to use xc_cpu_policy_t as a single object containing both the
> serialised and deserialised forms of the policy. Note that we need lengths
> for the arrays, as the serialised policies may be shorter than the array
> capacities.
>
> * Add the serialised lengths to the struct so we can distinguish
> between length and capacity of the serialisation buffers.
> * Remove explicit buffer+lengths in serialise/deserialise calls
> and use the internal buffer inside xc_cpu_policy_t instead.
> * Refactor everything to use the new serialisation functions.
> * Remove redundant serialization calls and avoid allocating dynamic
> memory aside from the policy objects in xen-cpuid. Also minor cleanup
> in the policy print call sites.
>
> No functional change intended.
>
> Signed-off-by: Alejandro Vallejo <alejandro.vallejo@cloud.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Just two comments.
> ---
> v3:
> * Better context scoping in xg_sr_common_x86.
> * Can't be const because write_record() takes non-const.
> * Adjusted line length of xen-cpuid's print_policy.
> * Adjusted error messages in xen-cpuid's print_policy.
> * Reverted removal of overscoped loop indices.
> ---
> tools/include/xenguest.h | 8 ++-
> tools/libs/guest/xg_cpuid_x86.c | 98 ++++++++++++++++++++---------
> tools/libs/guest/xg_private.h | 2 +
> tools/libs/guest/xg_sr_common_x86.c | 56 ++++++-----------
> tools/misc/xen-cpuid.c | 41 ++++--------
> 5 files changed, 106 insertions(+), 99 deletions(-)
>
> diff --git a/tools/include/xenguest.h b/tools/include/xenguest.h
> index e01f494b772a..563811cd8dde 100644
> --- a/tools/include/xenguest.h
> +++ b/tools/include/xenguest.h
> @@ -799,14 +799,16 @@ int xc_cpu_policy_set_domain(xc_interface *xch, uint32_t domid,
> xc_cpu_policy_t *policy);
>
> /* Manipulate a policy via architectural representations. */
> -int xc_cpu_policy_serialise(xc_interface *xch, const xc_cpu_policy_t *policy,
> - xen_cpuid_leaf_t *leaves, uint32_t *nr_leaves,
> - xen_msr_entry_t *msrs, uint32_t *nr_msrs);
> +int xc_cpu_policy_serialise(xc_interface *xch, xc_cpu_policy_t *policy);
> int xc_cpu_policy_update_cpuid(xc_interface *xch, xc_cpu_policy_t *policy,
> const xen_cpuid_leaf_t *leaves,
> uint32_t nr);
> int xc_cpu_policy_update_msrs(xc_interface *xch, xc_cpu_policy_t *policy,
> const xen_msr_entry_t *msrs, uint32_t nr);
> +int xc_cpu_policy_get_leaves(xc_interface *xch, const xc_cpu_policy_t *policy,
> + const xen_cpuid_leaf_t **leaves, uint32_t *nr);
> +int xc_cpu_policy_get_msrs(xc_interface *xch, const xc_cpu_policy_t *policy,
> + const xen_msr_entry_t **msrs, uint32_t *nr);
Maybe it would be helpful to have a comment clarifying that the return
of xc_cpu_policy_get_{leaves,msrs}() is a reference to the content of
the policy, not a copy of it (and hence is tied to the lifetime of
policy, and doesn't require explicit freeing).
>
> /* Compatibility calculations. */
> bool xc_cpu_policy_is_compatible(xc_interface *xch, xc_cpu_policy_t *host,
> diff --git a/tools/libs/guest/xg_cpuid_x86.c b/tools/libs/guest/xg_cpuid_x86.c
> index 4453178100ad..4f4b86b59470 100644
> --- a/tools/libs/guest/xg_cpuid_x86.c
> +++ b/tools/libs/guest/xg_cpuid_x86.c
> @@ -834,14 +834,13 @@ void xc_cpu_policy_destroy(xc_cpu_policy_t *policy)
> }
> }
>
> -static int deserialize_policy(xc_interface *xch, xc_cpu_policy_t *policy,
> - unsigned int nr_leaves, unsigned int nr_entries)
> +static int deserialize_policy(xc_interface *xch, xc_cpu_policy_t *policy)
> {
> uint32_t err_leaf = -1, err_subleaf = -1, err_msr = -1;
> int rc;
>
> rc = x86_cpuid_copy_from_buffer(&policy->policy, policy->leaves,
> - nr_leaves, &err_leaf, &err_subleaf);
> + policy->nr_leaves, &err_leaf, &err_subleaf);
> if ( rc )
> {
> if ( err_leaf != -1 )
> @@ -851,7 +850,7 @@ static int deserialize_policy(xc_interface *xch, xc_cpu_policy_t *policy,
> }
>
> rc = x86_msr_copy_from_buffer(&policy->policy, policy->msrs,
> - nr_entries, &err_msr);
> + policy->nr_msrs, &err_msr);
> if ( rc )
> {
> if ( err_msr != -1 )
> @@ -878,7 +877,10 @@ int xc_cpu_policy_get_system(xc_interface *xch, unsigned int policy_idx,
> return rc;
> }
>
> - rc = deserialize_policy(xch, policy, nr_leaves, nr_msrs);
> + policy->nr_leaves = nr_leaves;
> + policy->nr_msrs = nr_msrs;
> +
> + rc = deserialize_policy(xch, policy);
> if ( rc )
> {
> errno = -rc;
> @@ -903,7 +905,10 @@ int xc_cpu_policy_get_domain(xc_interface *xch, uint32_t domid,
> return rc;
> }
>
> - rc = deserialize_policy(xch, policy, nr_leaves, nr_msrs);
> + policy->nr_leaves = nr_leaves;
> + policy->nr_msrs = nr_msrs;
> +
> + rc = deserialize_policy(xch, policy);
> if ( rc )
> {
> errno = -rc;
> @@ -917,17 +922,14 @@ int xc_cpu_policy_set_domain(xc_interface *xch, uint32_t domid,
> xc_cpu_policy_t *policy)
> {
> uint32_t err_leaf = -1, err_subleaf = -1, err_msr = -1;
> - unsigned int nr_leaves = ARRAY_SIZE(policy->leaves);
> - unsigned int nr_msrs = ARRAY_SIZE(policy->msrs);
> int rc;
>
> - rc = xc_cpu_policy_serialise(xch, policy, policy->leaves, &nr_leaves,
> - policy->msrs, &nr_msrs);
> + rc = xc_cpu_policy_serialise(xch, policy);
> if ( rc )
> return rc;
>
> - rc = xc_set_domain_cpu_policy(xch, domid, nr_leaves, policy->leaves,
> - nr_msrs, policy->msrs,
> + rc = xc_set_domain_cpu_policy(xch, domid, policy->nr_leaves, policy->leaves,
> + policy->nr_msrs, policy->msrs,
> &err_leaf, &err_subleaf, &err_msr);
> if ( rc )
> {
> @@ -942,34 +944,32 @@ int xc_cpu_policy_set_domain(xc_interface *xch, uint32_t domid,
> return rc;
> }
>
> -int xc_cpu_policy_serialise(xc_interface *xch, const xc_cpu_policy_t *p,
> - xen_cpuid_leaf_t *leaves, uint32_t *nr_leaves,
> - xen_msr_entry_t *msrs, uint32_t *nr_msrs)
> +int xc_cpu_policy_serialise(xc_interface *xch, xc_cpu_policy_t *p)
> {
> + unsigned int nr_leaves = ARRAY_SIZE(p->leaves);
> + unsigned int nr_msrs = ARRAY_SIZE(p->msrs);
> int rc;
>
> - if ( leaves )
> + rc = x86_cpuid_copy_to_buffer(&p->policy, p->leaves, &nr_leaves);
> + if ( rc )
> {
> - rc = x86_cpuid_copy_to_buffer(&p->policy, leaves, nr_leaves);
> - if ( rc )
> - {
> - ERROR("Failed to serialize CPUID policy");
> - errno = -rc;
> - return -1;
> - }
> + ERROR("Failed to serialize CPUID policy");
> + errno = -rc;
> + return -1;
> }
>
> - if ( msrs )
> + p->nr_leaves = nr_leaves;
Nit: FWIW, I think you could avoid having to introduce local
nr_{leaves,msrs} variables and just use p->nr_{leaves,msrs}? By
setting them to ARRAY_SIZE() at the top of the function and then
letting x86_{cpuid,msr}_copy_to_buffer() adjust as necessary.
Thanks, Roger.
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v3 2/2] tools/xg: Clean up xend-style overrides for CPU policies
2024-05-23 9:41 ` [PATCH v3 2/2] tools/xg: Clean up xend-style overrides for CPU policies Alejandro Vallejo
@ 2024-05-23 10:47 ` Roger Pau Monné
2024-05-24 10:31 ` Alejandro Vallejo
0 siblings, 1 reply; 8+ messages in thread
From: Roger Pau Monné @ 2024-05-23 10:47 UTC (permalink / raw)
To: Alejandro Vallejo; +Cc: Xen-devel, Anthony PERARD, Juergen Gross
On Thu, May 23, 2024 at 10:41:30AM +0100, Alejandro Vallejo wrote:
> Factor out policy getters/setters from both (CPUID and MSR) policy override
> functions. Additionally, use host policy rather than featureset when
> preparing the cur policy, saving one hypercall and several lines of
> boilerplate.
>
> No functional change intended.
>
> Signed-off-by: Alejandro Vallejo <alejandro.vallejo@cloud.com>
> ---
> v3:
> * Restored overscoped loop indices
> * Split long line in conditional
> ---
> tools/libs/guest/xg_cpuid_x86.c | 438 ++++++++++----------------------
> 1 file changed, 131 insertions(+), 307 deletions(-)
>
> diff --git a/tools/libs/guest/xg_cpuid_x86.c b/tools/libs/guest/xg_cpuid_x86.c
> index 4f4b86b59470..1e631fd46d2f 100644
> --- a/tools/libs/guest/xg_cpuid_x86.c
> +++ b/tools/libs/guest/xg_cpuid_x86.c
> @@ -36,6 +36,34 @@ enum {
> #define bitmaskof(idx) (1u << ((idx) & 31))
> #define featureword_of(idx) ((idx) >> 5)
>
> +static int deserialize_policy(xc_interface *xch, xc_cpu_policy_t *policy)
> +{
> + uint32_t err_leaf = -1, err_subleaf = -1, err_msr = -1;
> + int rc;
> +
> + rc = x86_cpuid_copy_from_buffer(&policy->policy, policy->leaves,
> + policy->nr_leaves, &err_leaf, &err_subleaf);
> + if ( rc )
> + {
> + if ( err_leaf != -1 )
> + ERROR("Failed to deserialise CPUID (err leaf %#x, subleaf %#x) (%d = %s)",
> + err_leaf, err_subleaf, -rc, strerror(-rc));
> + return rc;
> + }
> +
> + rc = x86_msr_copy_from_buffer(&policy->policy, policy->msrs,
> + policy->nr_msrs, &err_msr);
> + if ( rc )
> + {
> + if ( err_msr != -1 )
> + ERROR("Failed to deserialise MSR (err MSR %#x) (%d = %s)",
> + err_msr, -rc, strerror(-rc));
> + return rc;
> + }
> +
> + return 0;
> +}
> +
> int xc_get_cpu_levelling_caps(xc_interface *xch, uint32_t *caps)
> {
> struct xen_sysctl sysctl = {};
> @@ -260,102 +288,37 @@ static int compare_leaves(const void *l, const void *r)
> return 0;
> }
>
> -static xen_cpuid_leaf_t *find_leaf(
> - xen_cpuid_leaf_t *leaves, unsigned int nr_leaves,
> - const struct xc_xend_cpuid *xend)
> +static xen_cpuid_leaf_t *find_leaf(xc_cpu_policy_t *p,
> + const struct xc_xend_cpuid *xend)
> {
> const xen_cpuid_leaf_t key = { xend->leaf, xend->subleaf };
>
> - return bsearch(&key, leaves, nr_leaves, sizeof(*leaves), compare_leaves);
> + return bsearch(&key, p->leaves, ARRAY_SIZE(p->leaves),
Don't you need to use p->nr_leaves here, as otherwise we could check
against possibly uninitialized leaves (or leaves with stale data)?
> + sizeof(*p->leaves), compare_leaves);
> }
>
> -static int xc_cpuid_xend_policy(
> - xc_interface *xch, uint32_t domid, const struct xc_xend_cpuid *xend)
> +static int xc_cpuid_xend_policy(xc_interface *xch, uint32_t domid,
> + const struct xc_xend_cpuid *xend,
> + xc_cpu_policy_t *host,
> + xc_cpu_policy_t *def,
> + xc_cpu_policy_t *cur)
> {
> - int rc;
> - bool hvm;
> - xc_domaininfo_t di;
> - unsigned int nr_leaves, nr_msrs;
> - uint32_t err_leaf = -1, err_subleaf = -1, err_msr = -1;
> - /*
> - * Three full policies. The host, default for the domain type,
> - * and domain current.
> - */
> - xen_cpuid_leaf_t *host = NULL, *def = NULL, *cur = NULL;
> - unsigned int nr_host, nr_def, nr_cur;
> -
> - if ( (rc = xc_domain_getinfo_single(xch, domid, &di)) < 0 )
> - {
> - PERROR("Failed to obtain d%d info", domid);
> - rc = -errno;
> - goto fail;
> - }
> - hvm = di.flags & XEN_DOMINF_hvm_guest;
> -
> - rc = xc_cpu_policy_get_size(xch, &nr_leaves, &nr_msrs);
> - if ( rc )
> - {
> - PERROR("Failed to obtain policy info size");
> - rc = -errno;
> - goto fail;
> - }
> -
> - rc = -ENOMEM;
> - if ( (host = calloc(nr_leaves, sizeof(*host))) == NULL ||
> - (def = calloc(nr_leaves, sizeof(*def))) == NULL ||
> - (cur = calloc(nr_leaves, sizeof(*cur))) == NULL )
> - {
> - ERROR("Unable to allocate memory for %u CPUID leaves", nr_leaves);
> - goto fail;
> - }
> -
> - /* Get the domain's current policy. */
> - nr_msrs = 0;
> - nr_cur = nr_leaves;
> - rc = get_domain_cpu_policy(xch, domid, &nr_cur, cur, &nr_msrs, NULL);
> - if ( rc )
> - {
> - PERROR("Failed to obtain d%d current policy", domid);
> - rc = -errno;
> - goto fail;
> - }
> + if ( !xend )
> + return 0;
>
> - /* Get the domain type's default policy. */
> - nr_msrs = 0;
> - nr_def = nr_leaves;
> - rc = get_system_cpu_policy(xch, hvm ? XEN_SYSCTL_cpu_policy_hvm_default
> - : XEN_SYSCTL_cpu_policy_pv_default,
> - &nr_def, def, &nr_msrs, NULL);
> - if ( rc )
> - {
> - PERROR("Failed to obtain %s def policy", hvm ? "hvm" : "pv");
> - rc = -errno;
> - goto fail;
> - }
> + if ( !host || !def || !cur )
> + return -EINVAL;
>
> - /* Get the host policy. */
> - nr_msrs = 0;
> - nr_host = nr_leaves;
> - rc = get_system_cpu_policy(xch, XEN_SYSCTL_cpu_policy_host,
> - &nr_host, host, &nr_msrs, NULL);
> - if ( rc )
> - {
> - PERROR("Failed to obtain host policy");
> - rc = -errno;
> - goto fail;
> - }
> -
> - rc = -EINVAL;
> for ( ; xend->leaf != XEN_CPUID_INPUT_UNUSED; ++xend )
> {
> - xen_cpuid_leaf_t *cur_leaf = find_leaf(cur, nr_cur, xend);
> - const xen_cpuid_leaf_t *def_leaf = find_leaf(def, nr_def, xend);
> - const xen_cpuid_leaf_t *host_leaf = find_leaf(host, nr_host, xend);
> + xen_cpuid_leaf_t *cur_leaf = find_leaf(cur, xend);
> + const xen_cpuid_leaf_t *def_leaf = find_leaf(def, xend);
> + const xen_cpuid_leaf_t *host_leaf = find_leaf(host, xend);
>
> if ( cur_leaf == NULL || def_leaf == NULL || host_leaf == NULL )
> {
> ERROR("Missing leaf %#x, subleaf %#x", xend->leaf, xend->subleaf);
> - goto fail;
> + return -EINVAL;
> }
>
> for ( unsigned int i = 0; i < ARRAY_SIZE(xend->policy); i++ )
> @@ -384,7 +347,7 @@ static int xc_cpuid_xend_policy(
> {
> ERROR("Bad character '%c' in policy[%d] string '%s'",
> xend->policy[i][j], i, xend->policy[i]);
> - goto fail;
> + return -EINVAL;
> }
>
> clear_bit(31 - j, cur_reg);
> @@ -394,25 +357,7 @@ static int xc_cpuid_xend_policy(
> }
> }
>
> - /* Feed the transformed currrent policy back up to Xen. */
> - rc = xc_set_domain_cpu_policy(xch, domid, nr_cur, cur, 0, NULL,
> - &err_leaf, &err_subleaf, &err_msr);
> - if ( rc )
> - {
> - PERROR("Failed to set d%d's policy (err leaf %#x, subleaf %#x, msr %#x)",
> - domid, err_leaf, err_subleaf, err_msr);
> - rc = -errno;
> - goto fail;
> - }
> -
> - /* Success! */
> -
> - fail:
> - free(cur);
> - free(def);
> - free(host);
> -
> - return rc;
> + return 0;
> }
>
> static int compare_msr(const void *l, const void *r)
> @@ -426,104 +371,38 @@ static int compare_msr(const void *l, const void *r)
> return lhs->idx < rhs->idx ? -1 : 1;
> }
>
> -static xen_msr_entry_t *find_msr(
> - xen_msr_entry_t *msrs, unsigned int nr_msrs,
> - uint32_t index)
> +static xen_msr_entry_t *find_msr(xc_cpu_policy_t *p,
> + uint32_t index)
> {
> const xen_msr_entry_t key = { .idx = index };
>
> - return bsearch(&key, msrs, nr_msrs, sizeof(*msrs), compare_msr);
> + return bsearch(&key, p->msrs, ARRAY_SIZE(p->msrs),
Same comment here regarding the usage of ARRAY_SIZE instead of
p->nr_msrs.
> + sizeof(*p->msrs), compare_msr);
> }
>
> -
> static int xc_msr_policy(xc_interface *xch, domid_t domid,
> - const struct xc_msr *msr)
> + const struct xc_msr *msr,
> + xc_cpu_policy_t *host,
> + xc_cpu_policy_t *def,
> + xc_cpu_policy_t *cur)
> {
> - int rc;
> - bool hvm;
> - xc_domaininfo_t di;
> - unsigned int nr_leaves, nr_msrs;
> - uint32_t err_leaf = -1, err_subleaf = -1, err_msr = -1;
> - /*
> - * Three full policies. The host, default for the domain type,
> - * and domain current.
> - */
> - xen_msr_entry_t *host = NULL, *def = NULL, *cur = NULL;
> - unsigned int nr_host, nr_def, nr_cur;
> -
> - if ( (rc = xc_domain_getinfo_single(xch, domid, &di)) < 0 )
> - {
> - PERROR("Failed to obtain d%d info", domid);
> - rc = -errno;
> - goto out;
> - }
> - hvm = di.flags & XEN_DOMINF_hvm_guest;
> -
> - rc = xc_cpu_policy_get_size(xch, &nr_leaves, &nr_msrs);
> - if ( rc )
> - {
> - PERROR("Failed to obtain policy info size");
> - rc = -errno;
> - goto out;
> - }
> -
> - if ( (host = calloc(nr_msrs, sizeof(*host))) == NULL ||
> - (def = calloc(nr_msrs, sizeof(*def))) == NULL ||
> - (cur = calloc(nr_msrs, sizeof(*cur))) == NULL )
> - {
> - ERROR("Unable to allocate memory for %u CPUID leaves", nr_leaves);
> - rc = -ENOMEM;
> - goto out;
> - }
> -
> - /* Get the domain's current policy. */
> - nr_leaves = 0;
> - nr_cur = nr_msrs;
> - rc = get_domain_cpu_policy(xch, domid, &nr_leaves, NULL, &nr_cur, cur);
> - if ( rc )
> - {
> - PERROR("Failed to obtain d%d current policy", domid);
> - rc = -errno;
> - goto out;
> - }
> -
> - /* Get the domain type's default policy. */
> - nr_leaves = 0;
> - nr_def = nr_msrs;
> - rc = get_system_cpu_policy(xch, hvm ? XEN_SYSCTL_cpu_policy_hvm_default
> - : XEN_SYSCTL_cpu_policy_pv_default,
> - &nr_leaves, NULL, &nr_def, def);
> - if ( rc )
> - {
> - PERROR("Failed to obtain %s def policy", hvm ? "hvm" : "pv");
> - rc = -errno;
> - goto out;
> - }
> + if ( !msr )
> + return 0;
>
> - /* Get the host policy. */
> - nr_leaves = 0;
> - nr_host = nr_msrs;
> - rc = get_system_cpu_policy(xch, XEN_SYSCTL_cpu_policy_host,
> - &nr_leaves, NULL, &nr_host, host);
> - if ( rc )
> - {
> - PERROR("Failed to obtain host policy");
> - rc = -errno;
> - goto out;
> - }
> + if ( !host || !def || !cur )
> + return -EINVAL;
>
> for ( ; msr->index != XC_MSR_INPUT_UNUSED; ++msr )
> {
> - xen_msr_entry_t *cur_msr = find_msr(cur, nr_cur, msr->index);
> - const xen_msr_entry_t *def_msr = find_msr(def, nr_def, msr->index);
> - const xen_msr_entry_t *host_msr = find_msr(host, nr_host, msr->index);
> unsigned int i;
> + xen_msr_entry_t *cur_msr = find_msr(cur, msr->index);
> + const xen_msr_entry_t *def_msr = find_msr(def, msr->index);
> + const xen_msr_entry_t *host_msr = find_msr(host, msr->index);
>
> if ( cur_msr == NULL || def_msr == NULL || host_msr == NULL )
> {
> ERROR("Missing MSR %#x", msr->index);
> - rc = -ENOENT;
> - goto out;
> + return -ENOENT;
> }
>
> for ( i = 0; i < ARRAY_SIZE(msr->policy) - 1; i++ )
> @@ -542,8 +421,7 @@ static int xc_msr_policy(xc_interface *xch, domid_t domid,
> {
> ERROR("MSR index %#x: bad character '%c' in policy string '%s'",
> msr->index, msr->policy[i], msr->policy);
> - rc = -EINVAL;
> - goto out;
> + return -EINVAL;
> }
>
> if ( val )
> @@ -553,25 +431,7 @@ static int xc_msr_policy(xc_interface *xch, domid_t domid,
> }
> }
>
> - /* Feed the transformed policy back up to Xen. */
> - rc = xc_set_domain_cpu_policy(xch, domid, 0, NULL, nr_cur, cur,
> - &err_leaf, &err_subleaf, &err_msr);
> - if ( rc )
> - {
> - PERROR("Failed to set d%d's policy (err leaf %#x, subleaf %#x, msr %#x)",
> - domid, err_leaf, err_subleaf, err_msr);
> - rc = -errno;
> - goto out;
> - }
> -
> - /* Success! */
> -
> - out:
> - free(cur);
> - free(def);
> - free(host);
> -
> - return rc;
> + return 0;
> }
>
> int xc_cpuid_apply_policy(xc_interface *xch, uint32_t domid, bool restore,
> @@ -583,14 +443,17 @@ int xc_cpuid_apply_policy(xc_interface *xch, uint32_t domid, bool restore,
> int rc;
> bool hvm;
> xc_domaininfo_t di;
> - struct xc_cpu_policy *p = xc_cpu_policy_init();
> - unsigned int i, nr_leaves = ARRAY_SIZE(p->leaves), nr_msrs = 0;
> - uint32_t err_leaf = -1, err_subleaf = -1, err_msr = -1;
> - uint32_t host_featureset[FEATURESET_NR_ENTRIES] = {};
> - uint32_t len = ARRAY_SIZE(host_featureset);
> + unsigned int i;
>
> - if ( !p )
> - return -ENOMEM;
> + struct xc_cpu_policy *host = xc_cpu_policy_init();
> + struct xc_cpu_policy *def = xc_cpu_policy_init();
> + struct xc_cpu_policy *cur = xc_cpu_policy_init();
> +
> + if ( !host || !def || !cur )
> + {
> + rc = -ENOMEM;
> + goto out;
> + }
>
> if ( (rc = xc_domain_getinfo_single(xch, domid, &di)) < 0 )
> {
> @@ -600,21 +463,19 @@ int xc_cpuid_apply_policy(xc_interface *xch, uint32_t domid, bool restore,
> }
> hvm = di.flags & XEN_DOMINF_hvm_guest;
>
> - /* Get the host policy. */
> - rc = xc_get_cpu_featureset(xch, XEN_SYSCTL_cpu_featureset_host,
> - &len, host_featureset);
> - /* Tolerate "buffer too small", as we've got the bits we need. */
> - if ( rc && errno != ENOBUFS )
> + /* Get the raw host policy */
> + rc = xc_cpu_policy_get_system(xch, XEN_SYSCTL_cpu_policy_host, host);
> + if ( rc )
> {
> - PERROR("Failed to obtain host featureset");
> + PERROR("Failed to obtain host policy");
> rc = -errno;
> goto out;
> }
>
> /* Get the domain's default policy. */
> - rc = get_system_cpu_policy(xch, hvm ? XEN_SYSCTL_cpu_policy_hvm_default
> - : XEN_SYSCTL_cpu_policy_pv_default,
> - &nr_leaves, p->leaves, &nr_msrs, NULL);
> + rc = xc_cpu_policy_get_system(xch, hvm ? XEN_SYSCTL_cpu_policy_hvm_default
> + : XEN_SYSCTL_cpu_policy_pv_default,
> + def);
> if ( rc )
> {
> PERROR("Failed to obtain %s default policy", hvm ? "hvm" : "pv");
> @@ -622,14 +483,8 @@ int xc_cpuid_apply_policy(xc_interface *xch, uint32_t domid, bool restore,
> goto out;
> }
>
> - rc = x86_cpuid_copy_from_buffer(&p->policy, p->leaves, nr_leaves,
> - &err_leaf, &err_subleaf);
> - if ( rc )
> - {
> - ERROR("Failed to deserialise CPUID (err leaf %#x, subleaf %#x) (%d = %s)",
> - err_leaf, err_subleaf, -rc, strerror(-rc));
> - goto out;
> - }
> + /* Copy the deserialised default policy to modify it */
> + memcpy(cur, def, sizeof(*cur));
>
> if ( restore )
> {
> @@ -647,18 +502,18 @@ int xc_cpuid_apply_policy(xc_interface *xch, uint32_t domid, bool restore,
> * - Re-enable features which have become (possibly) off by default.
> */
>
> - p->policy.basic.rdrand = test_bit(X86_FEATURE_RDRAND, host_featureset);
> - p->policy.feat.hle = test_bit(X86_FEATURE_HLE, host_featureset);
> - p->policy.feat.rtm = test_bit(X86_FEATURE_RTM, host_featureset);
> + cur->policy.basic.rdrand = host->policy.basic.rdrand;
> + cur->policy.feat.hle = host->policy.feat.hle;
> + cur->policy.feat.rtm = host->policy.feat.rtm;
>
> if ( hvm )
> {
> - p->policy.feat.mpx = test_bit(X86_FEATURE_MPX, host_featureset);
> + cur->policy.feat.mpx = host->policy.feat.mpx;
> }
>
> - p->policy.basic.max_leaf = min(p->policy.basic.max_leaf, 0xdu);
> - p->policy.feat.max_subleaf = 0;
> - p->policy.extd.max_leaf = min(p->policy.extd.max_leaf, 0x8000001c);
> + cur->policy.basic.max_leaf = min(cur->policy.basic.max_leaf, 0xdu);
> + cur->policy.feat.max_subleaf = 0;
> + cur->policy.extd.max_leaf = min(cur->policy.extd.max_leaf, 0x8000001c);
> }
>
> if ( featureset )
> @@ -702,17 +557,17 @@ int xc_cpuid_apply_policy(xc_interface *xch, uint32_t domid, bool restore,
> }
> }
>
> - x86_cpu_featureset_to_policy(feat, &p->policy);
> + x86_cpu_featureset_to_policy(feat, &cur->policy);
> }
> else
> {
> - p->policy.extd.itsc = itsc;
> + cur->policy.extd.itsc = itsc;
>
> if ( hvm )
> {
> - p->policy.basic.pae = pae;
> - p->policy.basic.vmx = nested_virt;
> - p->policy.extd.svm = nested_virt;
> + cur->policy.basic.pae = pae;
> + cur->policy.basic.vmx = nested_virt;
> + cur->policy.extd.svm = nested_virt;
> }
> }
>
> @@ -722,8 +577,8 @@ int xc_cpuid_apply_policy(xc_interface *xch, uint32_t domid, bool restore,
> * On hardware without CPUID Faulting, PV guests see real topology.
> * As a consequence, they also need to see the host htt/cmp fields.
> */
> - p->policy.basic.htt = test_bit(X86_FEATURE_HTT, host_featureset);
> - p->policy.extd.cmp_legacy = test_bit(X86_FEATURE_CMP_LEGACY, host_featureset);
> + cur->policy.basic.htt = host->policy.basic.htt;
> + cur->policy.extd.cmp_legacy = host->policy.extd.cmp_legacy;
> }
> else
> {
> @@ -731,28 +586,28 @@ int xc_cpuid_apply_policy(xc_interface *xch, uint32_t domid, bool restore,
> * Topology for HVM guests is entirely controlled by Xen. For now, we
> * hardcode APIC_ID = vcpu_id * 2 to give the illusion of no SMT.
> */
> - p->policy.basic.htt = true;
> - p->policy.extd.cmp_legacy = false;
> + cur->policy.basic.htt = true;
> + cur->policy.extd.cmp_legacy = false;
>
> /*
> * Leaf 1 EBX[23:16] is Maximum Logical Processors Per Package.
> * Update to reflect vLAPIC_ID = vCPU_ID * 2, but make sure to avoid
> * overflow.
> */
> - if ( !p->policy.basic.lppp )
> - p->policy.basic.lppp = 2;
> - else if ( !(p->policy.basic.lppp & 0x80) )
> - p->policy.basic.lppp *= 2;
> + if ( !cur->policy.basic.lppp )
> + cur->policy.basic.lppp = 2;
> + else if ( !(cur->policy.basic.lppp & 0x80) )
> + cur->policy.basic.lppp *= 2;
>
> - switch ( p->policy.x86_vendor )
> + switch ( cur->policy.x86_vendor )
> {
> case X86_VENDOR_INTEL:
> - for ( i = 0; (p->policy.cache.subleaf[i].type &&
> - i < ARRAY_SIZE(p->policy.cache.raw)); ++i )
> + for ( i = 0; (cur->policy.cache.subleaf[i].type &&
> + i < ARRAY_SIZE(cur->policy.cache.raw)); ++i )
Nit: indentation is weird here. I would use:
for ( i = 0; cur->policy.cache.subleaf[i].type &&
i < ARRAY_SIZE(cur->policy.cache.raw); ++i )
Thanks, Roger.
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v3 2/2] tools/xg: Clean up xend-style overrides for CPU policies
2024-05-23 10:47 ` Roger Pau Monné
@ 2024-05-24 10:31 ` Alejandro Vallejo
0 siblings, 0 replies; 8+ messages in thread
From: Alejandro Vallejo @ 2024-05-24 10:31 UTC (permalink / raw)
To: Roger Pau Monné; +Cc: Xen-devel, Anthony PERARD, Juergen Gross
On 23/05/2024 11:47, Roger Pau Monné wrote:
>> -static xen_cpuid_leaf_t *find_leaf(
>> - xen_cpuid_leaf_t *leaves, unsigned int nr_leaves,
>> - const struct xc_xend_cpuid *xend)
>> +static xen_cpuid_leaf_t *find_leaf(xc_cpu_policy_t *p,
>> + const struct xc_xend_cpuid *xend)
>> {
>> const xen_cpuid_leaf_t key = { xend->leaf, xend->subleaf };
>>
>> - return bsearch(&key, leaves, nr_leaves, sizeof(*leaves), compare_leaves);
>> + return bsearch(&key, p->leaves, ARRAY_SIZE(p->leaves),
>
> Don't you need to use p->nr_leaves here, as otherwise we could check
> against possibly uninitialized leaves (or leaves with stale data)?
Indeed. Good catch (same on the MSR side).
>> - switch ( p->policy.x86_vendor )
>> + switch ( cur->policy.x86_vendor )
>> {
>> case X86_VENDOR_INTEL:
>> - for ( i = 0; (p->policy.cache.subleaf[i].type &&
>> - i < ARRAY_SIZE(p->policy.cache.raw)); ++i )
>> + for ( i = 0; (cur->policy.cache.subleaf[i].type &&
>> + i < ARRAY_SIZE(cur->policy.cache.raw)); ++i )
>
> Nit: indentation is weird here. I would use:
>
> for ( i = 0; cur->policy.cache.subleaf[i].type &&
> i < ARRAY_SIZE(cur->policy.cache.raw); ++i )
>
> Thanks, Roger.
Sure. Leftover from removing the size_t in v2.
Cheers,
Alejandro
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v3 1/2] tools/xg: Streamline cpu policy serialise/deserialise calls
2024-05-23 10:21 ` Roger Pau Monné
@ 2024-05-24 10:32 ` Alejandro Vallejo
2024-05-24 11:02 ` Roger Pau Monné
0 siblings, 1 reply; 8+ messages in thread
From: Alejandro Vallejo @ 2024-05-24 10:32 UTC (permalink / raw)
To: Roger Pau Monné
Cc: Xen-devel, Anthony PERARD, Juergen Gross, Jan Beulich,
Andrew Cooper
On 23/05/2024 11:21, Roger Pau Monné wrote:
> On Thu, May 23, 2024 at 10:41:29AM +0100, Alejandro Vallejo wrote:
>> The idea is to use xc_cpu_policy_t as a single object containing both the
>> serialised and deserialised forms of the policy. Note that we need lengths
>> for the arrays, as the serialised policies may be shorter than the array
>> capacities.
>>
>> * Add the serialised lengths to the struct so we can distinguish
>> between length and capacity of the serialisation buffers.
>> * Remove explicit buffer+lengths in serialise/deserialise calls
>> and use the internal buffer inside xc_cpu_policy_t instead.
>> * Refactor everything to use the new serialisation functions.
>> * Remove redundant serialization calls and avoid allocating dynamic
>> memory aside from the policy objects in xen-cpuid. Also minor cleanup
>> in the policy print call sites.
>>
>> No functional change intended.
>>
>> Signed-off-by: Alejandro Vallejo <alejandro.vallejo@cloud.com>
>
> Acked-by: Roger Pau Monné <roger.pau@citrix.com>
>
> Just two comments.
>
>> ---
>> v3:
>> * Better context scoping in xg_sr_common_x86.
>> * Can't be const because write_record() takes non-const.
>> * Adjusted line length of xen-cpuid's print_policy.
>> * Adjusted error messages in xen-cpuid's print_policy.
>> * Reverted removal of overscoped loop indices.
>> ---
>> tools/include/xenguest.h | 8 ++-
>> tools/libs/guest/xg_cpuid_x86.c | 98 ++++++++++++++++++++---------
>> tools/libs/guest/xg_private.h | 2 +
>> tools/libs/guest/xg_sr_common_x86.c | 56 ++++++-----------
>> tools/misc/xen-cpuid.c | 41 ++++--------
>> 5 files changed, 106 insertions(+), 99 deletions(-)
>>
>> diff --git a/tools/include/xenguest.h b/tools/include/xenguest.h
>> index e01f494b772a..563811cd8dde 100644
>> --- a/tools/include/xenguest.h
>> +++ b/tools/include/xenguest.h
>> @@ -799,14 +799,16 @@ int xc_cpu_policy_set_domain(xc_interface *xch, uint32_t domid,
>> xc_cpu_policy_t *policy);
>>
>> /* Manipulate a policy via architectural representations. */
>> -int xc_cpu_policy_serialise(xc_interface *xch, const xc_cpu_policy_t *policy,
>> - xen_cpuid_leaf_t *leaves, uint32_t *nr_leaves,
>> - xen_msr_entry_t *msrs, uint32_t *nr_msrs);
>> +int xc_cpu_policy_serialise(xc_interface *xch, xc_cpu_policy_t *policy);
>> int xc_cpu_policy_update_cpuid(xc_interface *xch, xc_cpu_policy_t *policy,
>> const xen_cpuid_leaf_t *leaves,
>> uint32_t nr);
>> int xc_cpu_policy_update_msrs(xc_interface *xch, xc_cpu_policy_t *policy,
>> const xen_msr_entry_t *msrs, uint32_t nr);
>> +int xc_cpu_policy_get_leaves(xc_interface *xch, const xc_cpu_policy_t *policy,
>> + const xen_cpuid_leaf_t **leaves, uint32_t *nr);
>> +int xc_cpu_policy_get_msrs(xc_interface *xch, const xc_cpu_policy_t *policy,
>> + const xen_msr_entry_t **msrs, uint32_t *nr);
>
> Maybe it would be helpful to have a comment clarifying that the return
> of xc_cpu_policy_get_{leaves,msrs}() is a reference to the content of
> the policy, not a copy of it (and hence is tied to the lifetime of
> policy, and doesn't require explicit freeing).
Sure.
>
>>
>> /* Compatibility calculations. */
>> bool xc_cpu_policy_is_compatible(xc_interface *xch, xc_cpu_policy_t *host,
>> diff --git a/tools/libs/guest/xg_cpuid_x86.c b/tools/libs/guest/xg_cpuid_x86.c
>> index 4453178100ad..4f4b86b59470 100644
>> --- a/tools/libs/guest/xg_cpuid_x86.c
>> +++ b/tools/libs/guest/xg_cpuid_x86.c
>> @@ -834,14 +834,13 @@ void xc_cpu_policy_destroy(xc_cpu_policy_t *policy)
>> }
>> }
>>
>> -static int deserialize_policy(xc_interface *xch, xc_cpu_policy_t *policy,
>> - unsigned int nr_leaves, unsigned int nr_entries)
>> +static int deserialize_policy(xc_interface *xch, xc_cpu_policy_t *policy)
>> {
>> uint32_t err_leaf = -1, err_subleaf = -1, err_msr = -1;
>> int rc;
>>
>> rc = x86_cpuid_copy_from_buffer(&policy->policy, policy->leaves,
>> - nr_leaves, &err_leaf, &err_subleaf);
>> + policy->nr_leaves, &err_leaf, &err_subleaf);
>> if ( rc )
>> {
>> if ( err_leaf != -1 )
>> @@ -851,7 +850,7 @@ static int deserialize_policy(xc_interface *xch, xc_cpu_policy_t *policy,
>> }
>>
>> rc = x86_msr_copy_from_buffer(&policy->policy, policy->msrs,
>> - nr_entries, &err_msr);
>> + policy->nr_msrs, &err_msr);
>> if ( rc )
>> {
>> if ( err_msr != -1 )
>> @@ -878,7 +877,10 @@ int xc_cpu_policy_get_system(xc_interface *xch, unsigned int policy_idx,
>> return rc;
>> }
>>
>> - rc = deserialize_policy(xch, policy, nr_leaves, nr_msrs);
>> + policy->nr_leaves = nr_leaves;
>> + policy->nr_msrs = nr_msrs;
>> +
>> + rc = deserialize_policy(xch, policy);
>> if ( rc )
>> {
>> errno = -rc;
>> @@ -903,7 +905,10 @@ int xc_cpu_policy_get_domain(xc_interface *xch, uint32_t domid,
>> return rc;
>> }
>>
>> - rc = deserialize_policy(xch, policy, nr_leaves, nr_msrs);
>> + policy->nr_leaves = nr_leaves;
>> + policy->nr_msrs = nr_msrs;
>> +
>> + rc = deserialize_policy(xch, policy);
>> if ( rc )
>> {
>> errno = -rc;
>> @@ -917,17 +922,14 @@ int xc_cpu_policy_set_domain(xc_interface *xch, uint32_t domid,
>> xc_cpu_policy_t *policy)
>> {
>> uint32_t err_leaf = -1, err_subleaf = -1, err_msr = -1;
>> - unsigned int nr_leaves = ARRAY_SIZE(policy->leaves);
>> - unsigned int nr_msrs = ARRAY_SIZE(policy->msrs);
>> int rc;
>>
>> - rc = xc_cpu_policy_serialise(xch, policy, policy->leaves, &nr_leaves,
>> - policy->msrs, &nr_msrs);
>> + rc = xc_cpu_policy_serialise(xch, policy);
>> if ( rc )
>> return rc;
>>
>> - rc = xc_set_domain_cpu_policy(xch, domid, nr_leaves, policy->leaves,
>> - nr_msrs, policy->msrs,
>> + rc = xc_set_domain_cpu_policy(xch, domid, policy->nr_leaves, policy->leaves,
>> + policy->nr_msrs, policy->msrs,
>> &err_leaf, &err_subleaf, &err_msr);
>> if ( rc )
>> {
>> @@ -942,34 +944,32 @@ int xc_cpu_policy_set_domain(xc_interface *xch, uint32_t domid,
>> return rc;
>> }
>>
>> -int xc_cpu_policy_serialise(xc_interface *xch, const xc_cpu_policy_t *p,
>> - xen_cpuid_leaf_t *leaves, uint32_t *nr_leaves,
>> - xen_msr_entry_t *msrs, uint32_t *nr_msrs)
>> +int xc_cpu_policy_serialise(xc_interface *xch, xc_cpu_policy_t *p)
>> {
>> + unsigned int nr_leaves = ARRAY_SIZE(p->leaves);
>> + unsigned int nr_msrs = ARRAY_SIZE(p->msrs);
>> int rc;
>>
>> - if ( leaves )
>> + rc = x86_cpuid_copy_to_buffer(&p->policy, p->leaves, &nr_leaves);
>> + if ( rc )
>> {
>> - rc = x86_cpuid_copy_to_buffer(&p->policy, leaves, nr_leaves);
>> - if ( rc )
>> - {
>> - ERROR("Failed to serialize CPUID policy");
>> - errno = -rc;
>> - return -1;
>> - }
>> + ERROR("Failed to serialize CPUID policy");
>> + errno = -rc;
>> + return -1;
>> }
>>
>> - if ( msrs )
>> + p->nr_leaves = nr_leaves;
>
> Nit: FWIW, I think you could avoid having to introduce local
> nr_{leaves,msrs} variables and just use p->nr_{leaves,msrs}? By
> setting them to ARRAY_SIZE() at the top of the function and then
> letting x86_{cpuid,msr}_copy_to_buffer() adjust as necessary.
>
> Thanks, Roger.
The intent was to avoid mutating the policy object in the error cases
during deserialise. Then I adjusted the serialise case to have symmetry.
It's true the preservation is not meaningful in the serialise case
because at that point the serialised form is already corrupted.
I don't mind either way. Seeing how I'm sending one final version with
the comments of patch2 I'll just adjust as you proposed.
Cheers,
Alejandro
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v3 1/2] tools/xg: Streamline cpu policy serialise/deserialise calls
2024-05-24 10:32 ` Alejandro Vallejo
@ 2024-05-24 11:02 ` Roger Pau Monné
0 siblings, 0 replies; 8+ messages in thread
From: Roger Pau Monné @ 2024-05-24 11:02 UTC (permalink / raw)
To: Alejandro Vallejo
Cc: Xen-devel, Anthony PERARD, Juergen Gross, Jan Beulich,
Andrew Cooper
On Fri, May 24, 2024 at 11:32:50AM +0100, Alejandro Vallejo wrote:
> On 23/05/2024 11:21, Roger Pau Monné wrote:
> > On Thu, May 23, 2024 at 10:41:29AM +0100, Alejandro Vallejo wrote:
> >> -int xc_cpu_policy_serialise(xc_interface *xch, const xc_cpu_policy_t *p,
> >> - xen_cpuid_leaf_t *leaves, uint32_t *nr_leaves,
> >> - xen_msr_entry_t *msrs, uint32_t *nr_msrs)
> >> +int xc_cpu_policy_serialise(xc_interface *xch, xc_cpu_policy_t *p)
> >> {
> >> + unsigned int nr_leaves = ARRAY_SIZE(p->leaves);
> >> + unsigned int nr_msrs = ARRAY_SIZE(p->msrs);
> >> int rc;
> >>
> >> - if ( leaves )
> >> + rc = x86_cpuid_copy_to_buffer(&p->policy, p->leaves, &nr_leaves);
> >> + if ( rc )
> >> {
> >> - rc = x86_cpuid_copy_to_buffer(&p->policy, leaves, nr_leaves);
> >> - if ( rc )
> >> - {
> >> - ERROR("Failed to serialize CPUID policy");
> >> - errno = -rc;
> >> - return -1;
> >> - }
> >> + ERROR("Failed to serialize CPUID policy");
> >> + errno = -rc;
> >> + return -1;
> >> }
> >>
> >> - if ( msrs )
> >> + p->nr_leaves = nr_leaves;
> >
> > Nit: FWIW, I think you could avoid having to introduce local
> > nr_{leaves,msrs} variables and just use p->nr_{leaves,msrs}? By
> > setting them to ARRAY_SIZE() at the top of the function and then
> > letting x86_{cpuid,msr}_copy_to_buffer() adjust as necessary.
> >
> > Thanks, Roger.
>
> The intent was to avoid mutating the policy object in the error cases
> during deserialise. Then I adjusted the serialise case to have symmetry.
It's currently unavoidable for the policy to be likely mutated even in
case of error, as x86_{cpuid,msr}_copy_to_buffer() are two separate
operations, and hence the first succeeding but the second failing will
already result in the policy being mutated on error.
> It's true the preservation is not meaningful in the serialise case
> because at that point the serialised form is already corrupted.
>
> I don't mind either way. Seeing how I'm sending one final version with
> the comments of patch2 I'll just adjust as you proposed.
I'm fine either way (hence why prefix it with "nit:") albeit I have a
preference for not introducing the local variables if they are not
needed.
Thanks, Roger.
^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2024-05-24 11:03 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2024-05-23 9:41 [PATCH v3 0/2] Clean the policy manipulation path in domain creation Alejandro Vallejo
2024-05-23 9:41 ` [PATCH v3 1/2] tools/xg: Streamline cpu policy serialise/deserialise calls Alejandro Vallejo
2024-05-23 10:21 ` Roger Pau Monné
2024-05-24 10:32 ` Alejandro Vallejo
2024-05-24 11:02 ` Roger Pau Monné
2024-05-23 9:41 ` [PATCH v3 2/2] tools/xg: Clean up xend-style overrides for CPU policies Alejandro Vallejo
2024-05-23 10:47 ` Roger Pau Monné
2024-05-24 10:31 ` Alejandro Vallejo
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