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 )
--
2.34.1On 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.
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
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.
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