[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v8 08/24] x86: refactor psr: set value: implement framework.
On Wed, Feb 15, 2017 at 04:49:23PM +0800, Yi Sun wrote: > As set value flow is the most complicated one in psr, it will be > divided to some patches to make things clearer. This patch > implements the set value framework to show a whole picture firstly. > > It also changes domctl interface to make it more general. > > To make the set value flow be general and can support multiple features > at same time, it includes below steps: > 1. Get COS ID of current domain using. > 2. Assemble a value array to store all features current value > in it and replace the current value of the feature which is > being set to the new input value. > 3. Find if there is already a COS ID on which all features' > values are same as the array. Then, we can reuse this COS > ID. > 4. If fail to find, we need pick an available COS ID. Only COS ID which ref > is 0 or 1 can be picked. > 5. Write all features MSRs according to the COS ID. > 6. Update ref according to COS ID. > 7. Save the COS ID into current domain's psr_cos_ids[socket] so that we > can know which COS the domain is using on the socket. > > So, some functions are abstracted and the callback functions will be > implemented in next patches. > > Here is an example to understand the process. The CPU supports > two featuers, e.g. L3 CAT and L2 CAT. user wants to set L3 CAT > of Dom1 to 0x1ff. > 1. Get the old_cos of Dom1 which is 0. L3 CAT is the first > element of feature list. The COS registers values are below at > this time. > ------------------------------- > | COS 0 | COS 1 | COS 2 | ... | > ------------------------------- > L3 CAT | 0x7ff | ... | ... | ... | > ------------------------------- > L2 CAT | 0xff | ... | ... | ... | > ------------------------------- > > 2. Assemble The value array to be: > val[0]: 0x1ff > val[1]: 0xff > > 3. It cannot find a matching COS. > > 4. Allocate COS 1 to store the value set. > > 5. Write the COS 1 registers. The COS registers values are > changed to below now. > ------------------------------- > | COS 0 | COS 1 | COS 2 | ... | > ------------------------------- > L3 CAT | 0x7ff | 0x1ff | ... | ... | > ------------------------------- > L2 CAT | 0xff | 0xff | ... | ... | > ------------------------------- > > 6. The ref[1] is increased to 1 because Dom1 is using it now. > > 7. Save 1 to Dom1's psr_cos_ids[socket]. > > Then, user wants to set L3 CAT of Dom2 to 0x1ff too. The old_cos > of Dom2 is 0 too. Repeat above flow. > > The val array assembled is: > val[0]: 0x1ff > val[1]: 0xff > > So, it can find a matching COS, COS 1. Then, it can reuse COS 1 > for Dom2. > > The ref[1] is increased to 2 now because both Dom1 and Dom2 are > using this COS ID. Set 1 to Dom2's psr_cos_ids[socket]. > > Signed-off-by: Yi Sun <yi.y.sun@xxxxxxxxxxxxxxx> > --- > xen/arch/x86/domctl.c | 18 ++--- > xen/arch/x86/psr.c | 202 > +++++++++++++++++++++++++++++++++++++++++++++- > xen/include/asm-x86/psr.h | 4 +- > 3 files changed, 210 insertions(+), 14 deletions(-) [...] > diff --git a/xen/arch/x86/psr.c b/xen/arch/x86/psr.c > index c1afd36..d414b5e 100644 > --- a/xen/arch/x86/psr.c > +++ b/xen/arch/x86/psr.c > @@ -546,18 +546,214 @@ int psr_get_val(struct domain *d, unsigned int socket, > return psr_get(socket, type, NULL, 0, d, val); > } > > -int psr_set_l3_cbm(struct domain *d, unsigned int socket, > - uint64_t cbm, enum cbm_type type) > +/* Set value functions */ > +static unsigned int get_cos_num(const struct psr_socket_info *info) > { > return 0; > } > > +static int assemble_val_array(uint64_t *val, > + uint32_t array_len, > + const struct psr_socket_info *info, > + unsigned int old_cos) > +{ > + return -EINVAL; > +} > + > +static int set_new_val_to_array(uint64_t *val, > + uint32_t array_len, > + const struct psr_socket_info *info, > + enum psr_feat_type feat_type, > + enum cbm_type type, > + uint64_t m) > +{ > + return -EINVAL; > +} > + > +static int find_cos(const uint64_t *val, uint32_t array_len, > + enum psr_feat_type feat_type, > + const struct psr_socket_info *info) > +{ ASSERT(spin_is_locked(info->ref_lock)); > + return -ENOENT; > +} > + > +static int pick_avail_cos(const struct psr_socket_info *info, > + const uint64_t *val, uint32_t array_len, > + unsigned int old_cos, > + enum psr_feat_type feat_type) > +{ ASSERT(spin_is_locked(info->ref_lock)); > + return -ENOENT; > +} > + > +static int write_psr_msr(unsigned int socket, unsigned int cos, > + const uint64_t *val) > +{ ASSERT(spin_is_locked(info->ref_lock)); > + return -ENOENT; > +} > + > +int psr_set_val(struct domain *d, unsigned int socket, > + uint64_t val, enum cbm_type type) > +{ > + unsigned int old_cos; > + int cos, ret; > + unsigned int *ref; > + uint64_t *val_array; > + struct psr_socket_info *info = get_socket_info(socket); > + uint32_t array_len; > + enum psr_feat_type feat_type; > + > + if ( IS_ERR(info) ) > + return PTR_ERR(info); > + > + feat_type = psr_cbm_type_to_feat_type(type); > + if ( !test_bit(feat_type, &info->feat_mask) ) > + return -ENOENT; > + > + /* > + * Step 0: > + * old_cos means the COS ID current domain is using. By default, it is 0. > + * > + * For every COS ID, there is a reference count to record how many > domains > + * are using the COS register corresponding to this COS ID. > + * - If ref[old_cos] is 0, that means this COS is not used by any domain. > + * - If ref[old_cos] is 1, that means this COS is only used by current > + * domain. > + * - If ref[old_cos] is more than 1, that mean multiple domains are using > + * this COS. > + */ > + old_cos = d->arch.psr_cos_ids[socket]; > + if ( old_cos > MAX_COS_REG_CNT ) > + return -EOVERFLOW; > + > + ref = info->cos_ref; > + > + /* > + * Step 1: > + * Assemle a value array to store all featues cos_reg_val[old_cos]. > + * And, set the input val into array according to the feature's > + * position in array. > + */ > + array_len = get_cos_num(info); > + val_array = xzalloc_array(uint64_t, array_len); > + if ( !val_array ) > + return -ENOMEM; > + > + if ( (ret = assemble_val_array(val_array, array_len, info, old_cos)) != > 0 ) > + { > + xfree(val_array); > + return ret; > + } > + > + if ( (ret = set_new_val_to_array(val_array, array_len, info, > + feat_type, type, val)) != 0 ) > + { > + xfree(val_array); > + return ret; > + } > + > + /* > + * Lock here to make sure the ref is not changed during find and > + * write process. > + */ > + spin_lock(&info->ref_lock); > + > + /* > + * Step 2: > + * Try to find if there is already a COS ID on which all features' values > + * are same as the array. Then, we can reuse this COS ID. > + */ > + cos = find_cos(val_array, array_len, feat_type, info); > + if ( cos >= 0 ) > + { > + if ( cos == old_cos ) > + { > + spin_unlock(&info->ref_lock); > + xfree(val_array); > + return 0; > + } > + } > + else > + { > + /* > + * Step 3: > + * If fail to find, we need allocate a new COS ID. > + * If multiple domains are using same COS ID, its ref is more > + * than 1. That means we cannot free this COS to make current domain > + * use it. Because other domains are using the value saved in the > COS. > + * Unless the ref is changed to 1 (mean only current domain is using > + * it), we cannot allocate the COS ID to current domain. > + * So, only the COS ID which ref is 1 or 0 can be allocated. > + */ > + cos = pick_avail_cos(info, val_array, array_len, old_cos, feat_type); > + if ( cos < 0 ) > + { > + spin_unlock(&info->ref_lock); > + xfree(val_array); > + return cos; > + } > + > + /* > + * Step 4: > + * Write all features MSRs according to the COS ID. > + */ > + ret = write_psr_msr(socket, cos, val_array); > + if ( ret ) > + { > + spin_unlock(&info->ref_lock); > + xfree(val_array); > + return ret; > + } > + } > + > + /* > + * Step 5: > + * Update ref according to COS ID. > + */ > + ref[cos]++; > + ASSERT(ref[cos] || cos == 0); > + ref[old_cos]--; If cos == 0 you can overflow ref[0]. > + spin_unlock(&info->ref_lock); > + > + /* > + * Step 6: > + * Save the COS ID into current domain's psr_cos_ids[] so that we can > know > + * which COS the domain is using on the socket. One domain can only use > + * one COS ID at same time on each socket. > + */ > + d->arch.psr_cos_ids[socket] = cos; > + xfree(val_array); > + > + return 0; > +} > + > /* Called with domain lock held, no extra lock needed for 'psr_cos_ids' */ > static void psr_free_cos(struct domain *d) > { > - if( !d->arch.psr_cos_ids ) > + unsigned int socket, cos; An ASSERT that the domain is locked would be better than a comment. > + if ( !d->arch.psr_cos_ids ) > return; > > + /* Domain is free so its cos_ref should be decreased. */ > + for ( socket = 0; socket < nr_sockets; socket++ ) > + { > + struct psr_socket_info *info; > + > + /* cos 0 is default one which does not need be handled. */ > + if ( (cos = d->arch.psr_cos_ids[socket]) == 0 ) > + continue; > + > + /* > + * If domain uses other cos ids, all corresponding refs must have > been > + * increased 1 for this domain. So, we need decrease them. > + */ > + info = socket_info + socket; > + ASSERT(info->cos_ref[cos] || cos == 0); > + spin_lock(&info->ref_lock); > + info->cos_ref[cos]--; If cos == 0, it is possible to reach this with info->cos_ref[cos] == 0, in which case you are overflowing it? > + spin_unlock(&info->ref_lock); > + } > + > xfree(d->arch.psr_cos_ids); > d->arch.psr_cos_ids = NULL; > } > diff --git a/xen/include/asm-x86/psr.h b/xen/include/asm-x86/psr.h > index 569e7df..fde7882 100644 > --- a/xen/include/asm-x86/psr.h > +++ b/xen/include/asm-x86/psr.h > @@ -72,8 +72,8 @@ int psr_get_info(unsigned int socket, enum cbm_type type, > uint32_t data[], unsigned int array_len); > int psr_get_val(struct domain *d, unsigned int socket, > uint64_t *val, enum cbm_type type); > -int psr_set_l3_cbm(struct domain *d, unsigned int socket, > - uint64_t cbm, enum cbm_type type); > +int psr_set_val(struct domain *d, unsigned int socket, > + uint64_t val, enum cbm_type type); > > int psr_domain_init(struct domain *d); > void psr_domain_free(struct domain *d); > -- > 1.9.1 > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@xxxxxxxxxxxxx > https://lists.xen.org/xen-devel _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
|
![]() |
Lists.xenproject.org is hosted with RackSpace, monitoring our |