Introduce support for allocating and initializing the root page table
required for RISC-V stage-2 address translation.
To implement root page table allocation the following is introduced:
- p2m_get_clean_page() and p2m_alloc_root_table(), p2m_allocate_root()
helpers to allocate and zero a 16 KiB root page table, as mandated
by the RISC-V privileged specification for Sv32x4/Sv39x4/Sv48x4/Sv57x4
modes.
- Update p2m_init() to inititialize p2m_root_order.
- Add maddr_to_page() and page_to_maddr() macros for easier address
manipulation.
- Introduce paging_ret_pages_to_domheap() to return some pages before
allocate 16 KiB pages for root page table.
- Allocate root p2m table after p2m pool is initialized.
- Add construct_hgatp() to construct the hgatp register value based on
p2m->root, p2m->hgatp_mode and VMID.
Signed-off-by: Oleksii Kurochko <oleksii.kuroc...@gmail.com>
---
Changes in v3:
- Drop insterting of p2m->vmid in hgatp_from_page() as now vmid is allocated
per-CPU, not per-domain, so it will be inserted later somewhere in
context_switch or before returning control to a guest.
- use BIT() to init nr_pages in p2m_allocate_root() instead of open-code
BIT() macros.
- Fix order in clear_and_clean_page().
- s/panic("Specify more xen,domain-p2m-mem-mb\n")/return NULL.
- Use lock around a procedure of returning back pages necessary for p2m
root table.
- Update the comment about allocation of page for root page table.
- Update an argument of hgatp_from_page() to "struct page_info *p2m_root_page"
to be consistent with the function name.
- Use p2m_get_hostp2m(d) instead of open-coding it.
- Update the comment above the call of p2m_alloc_root_table().
- Update the comments in p2m_allocate_root().
- Move part which returns some page to domheap before root page table
allocation
to paging.c.
- Pass p2m_domain * instead of struct domain * for p2m_alloc_root_table().
- Introduce construct_hgatp() instead of hgatp_from_page().
- Add vmid and hgatp_mode member of struct p2m_domain.
- Add explanatory comment above clean_dcache_va_range() in
clear_and_clean_page().
- Introduce P2M_ROOT_ORDER and P2M_ROOT_PAGES.
- Drop vmid member from p2m_domain as now we are using per-pCPU
VMID allocation.
- Update a declaration of construct_hgatp() to recieve VMID as it
isn't per-VM anymore.
- Drop hgatp member of p2m_domain struct as with the new VMID scheme
allocation construction of hgatp will be needed more often.
- Drop is_hardware_domain() case in p2m_allocate_root(), just always
allocate root using p2m pool pages.
- Refactor p2m_alloc_root_table() and p2m_alloc_table().
---
Changes in v2:
- This patch was created from "xen/riscv: introduce things necessary for p2m
initialization" with the following changes:
- [clear_and_clean_page()] Add missed call of clean_dcache_va_range().
- Drop p2m_get_clean_page() as it is going to be used only once to allocate
root page table. Open-code it explicittly in p2m_allocate_root(). Also,
it will help avoid duplication of the code connected to order and nr_pages
of p2m root page table.
- Instead of using order 2 for alloc_domheap_pages(), use
get_order_from_bytes(KB(16)).
- Clear and clean a proper amount of allocated pages in p2m_allocate_root().
- Drop _info from the function name hgatp_from_page_info() and its argument
page_info.
- Introduce HGATP_MODE_MASK and use MASK_INSR() instead of shift to calculate
value of hgatp.
- Drop unnecessary parentheses in definition of page_to_maddr().
- Add support of VMID.
- Drop TLB flushing in p2m_alloc_root_table() and do that once when VMID
is re-used. [Look at p2m_alloc_vmid()]
- Allocate p2m root table after p2m pool is fully initialized: first
return pages to p2m pool them allocate p2m root table.
---
xen/arch/riscv/include/asm/mm.h | 4 +
xen/arch/riscv/include/asm/p2m.h | 12 +++
xen/arch/riscv/include/asm/paging.h | 2 +
xen/arch/riscv/include/asm/riscv_encoding.h | 6 ++
xen/arch/riscv/p2m.c | 90 +++++++++++++++++++++
xen/arch/riscv/paging.c | 30 +++++++
6 files changed, 144 insertions(+)
diff --git a/xen/arch/riscv/include/asm/mm.h b/xen/arch/riscv/include/asm/mm.h
index 9283616c02..dd8cdc9782 100644
--- a/xen/arch/riscv/include/asm/mm.h
+++ b/xen/arch/riscv/include/asm/mm.h
@@ -167,6 +167,10 @@ extern struct page_info *frametable_virt_start;
#define mfn_to_page(mfn) (frametable_virt_start + mfn_x(mfn))
#define page_to_mfn(pg) _mfn((pg) - frametable_virt_start)
+/* Convert between machine addresses and page-info structures. */
+#define maddr_to_page(ma) mfn_to_page(maddr_to_mfn(ma))
+#define page_to_maddr(pg) mfn_to_maddr(page_to_mfn(pg))
+
static inline void *page_to_virt(const struct page_info *pg)
{
return mfn_to_virt(mfn_x(page_to_mfn(pg)));
diff --git a/xen/arch/riscv/include/asm/p2m.h b/xen/arch/riscv/include/asm/p2m.h
index f8051ed893..3c37a708db 100644
--- a/xen/arch/riscv/include/asm/p2m.h
+++ b/xen/arch/riscv/include/asm/p2m.h
@@ -9,6 +9,10 @@
#include <asm/page-bits.h>
+extern unsigned int p2m_root_order;
+#define P2M_ROOT_ORDER p2m_root_order
+#define P2M_ROOT_PAGES BIT(P2M_ROOT_ORDER, U)
+
#define paddr_bits PADDR_BITS
/* Get host p2m table */
@@ -24,6 +28,12 @@ struct p2m_domain {
/* Pages used to construct the p2m */
struct page_list_head pages;
+ /* The root of the p2m tree. May be concatenated */
+ struct page_info *root;
+
+ /* G-stage (stage-2) address translation mode */
+ unsigned long hgatp_mode;
+
/* Indicate if it is required to clean the cache when writing an entry */
bool clean_pte;
@@ -127,6 +137,8 @@ static inline void p2m_altp2m_check(struct vcpu *v,
uint16_t idx)
/* Not supported on RISCV. */
}
+unsigned long construct_hgatp(struct p2m_domain *p2m, uint16_t vmid);
+
#endif /* ASM__RISCV__P2M_H */
/*
diff --git a/xen/arch/riscv/include/asm/paging.h
b/xen/arch/riscv/include/asm/paging.h
index 8fdaeeb2e4..557fbd1abc 100644
--- a/xen/arch/riscv/include/asm/paging.h
+++ b/xen/arch/riscv/include/asm/paging.h
@@ -10,4 +10,6 @@ int paging_domain_init(struct domain *d);
int paging_freelist_init(struct domain *d, unsigned long pages,
bool *preempted);
+bool paging_ret_pages_to_domheap(struct domain *d, unsigned int nr_pages);
+
#endif /* ASM_RISCV_PAGING_H */
diff --git a/xen/arch/riscv/include/asm/riscv_encoding.h
b/xen/arch/riscv/include/asm/riscv_encoding.h
index 6cc8f4eb45..8362df8784 100644
--- a/xen/arch/riscv/include/asm/riscv_encoding.h
+++ b/xen/arch/riscv/include/asm/riscv_encoding.h
@@ -133,11 +133,13 @@
#define HGATP_MODE_SV48X4 _UL(9)
#define HGATP32_MODE_SHIFT 31
+#define HGATP32_MODE_MASK _UL(0x80000000)
#define HGATP32_VMID_SHIFT 22
#define HGATP32_VMID_MASK _UL(0x1FC00000)
#define HGATP32_PPN _UL(0x003FFFFF)
#define HGATP64_MODE_SHIFT 60
+#define HGATP64_MODE_MASK _ULL(0xF000000000000000)
#define HGATP64_VMID_SHIFT 44
#define HGATP64_VMID_MASK _ULL(0x03FFF00000000000)
#define HGATP64_PPN _ULL(0x00000FFFFFFFFFFF)
@@ -170,6 +172,7 @@
#define HGATP_VMID_SHIFT HGATP64_VMID_SHIFT
#define HGATP_VMID_MASK HGATP64_VMID_MASK
#define HGATP_MODE_SHIFT HGATP64_MODE_SHIFT
+#define HGATP_MODE_MASK HGATP64_MODE_MASK
#else
#define MSTATUS_SD MSTATUS32_SD
#define SSTATUS_SD SSTATUS32_SD
@@ -181,8 +184,11 @@
#define HGATP_VMID_SHIFT HGATP32_VMID_SHIFT
#define HGATP_VMID_MASK HGATP32_VMID_MASK
#define HGATP_MODE_SHIFT HGATP32_MODE_SHIFT
+#define HGATP_MODE_MASK HGATP32_MODE_MASK
#endif
+#define GUEST_ROOT_PAGE_TABLE_SIZE KB(16)
+
#define TOPI_IID_SHIFT 16
#define TOPI_IID_MASK 0xfff
#define TOPI_IPRIO_MASK 0xff
diff --git a/xen/arch/riscv/p2m.c b/xen/arch/riscv/p2m.c
index 214b4861d2..cac07c51c9 100644
--- a/xen/arch/riscv/p2m.c
+++ b/xen/arch/riscv/p2m.c
@@ -1,8 +1,86 @@
+#include <xen/domain_page.h>
#include <xen/mm.h>
#include <xen/rwlock.h>
#include <xen/sched.h>
#include <asm/paging.h>
+#include <asm/p2m.h>
+#include <asm/riscv_encoding.h>
+
+unsigned int __read_mostly p2m_root_order;
+
+static void clear_and_clean_page(struct page_info *page)
+{
+ clear_domain_page(page_to_mfn(page));
+
+ /*
+ * If the IOMMU doesn't support coherent walks and the p2m tables are
+ * shared between the CPU and IOMMU, it is necessary to clean the
+ * d-cache.
+ */
+ clean_dcache_va_range(page, PAGE_SIZE);
+}
+
+static struct page_info *p2m_allocate_root(struct domain *d)
+{
+ struct page_info *page;
+
+ /*
+ * As mentioned in the Priviliged Architecture Spec (version 20240411)
+ * in Section 18.5.1, for the paged virtual-memory schemes (Sv32x4,
+ * Sv39x4, Sv48x4, and Sv57x4), the root page table is 16 KiB and must
+ * be aligned to a 16-KiB boundary.
+ */
+ page = alloc_domheap_pages(d, P2M_ROOT_ORDER, MEMF_no_owner);
+ if ( !page )
+ return NULL;
+
+ for ( unsigned int i = 0; i < P2M_ROOT_PAGES; i++ )
+ clear_and_clean_page(page + i);
+
+ return page;
+}
+
+unsigned long construct_hgatp(struct p2m_domain *p2m, uint16_t vmid)
+{
+ unsigned long ppn;
+
+ ppn = PFN_DOWN(page_to_maddr(p2m->root)) & HGATP_PPN;
+
+ /* TODO: add detection of hgatp_mode instead of hard-coding it. */
+#if RV_STAGE1_MODE == SATP_MODE_SV39
+ p2m->hgatp_mode = HGATP_MODE_SV39X4;
+#elif RV_STAGE1_MODE == SATP_MODE_SV48
+ p2m->hgatp_mode = HGATP_MODE_SV48X4;
+#else
+# error "add HGATP_MODE"
+#endif
+
+ return ppn | MASK_INSR(p2m->hgatp_mode, HGATP_MODE_MASK) |
+ MASK_INSR(vmid, HGATP_VMID_MASK);
+}
+
+static int p2m_alloc_root_table(struct p2m_domain *p2m)
+{
+ struct domain *d = p2m->domain;
+ struct page_info *page;
+ const unsigned int nr_root_pages = P2M_ROOT_PAGES;
+
+ /*
+ * Return back nr_root_pages to assure the root table memory is also
+ * accounted against the P2M pool of the domain.
+ */
+ if ( !paging_ret_pages_to_domheap(d, nr_root_pages) )
+ return -ENOMEM;
+
+ page = p2m_allocate_root(d);
+ if ( !page )
+ return -ENOMEM;
+
+ p2m->root = page;
+
+ return 0;
+}
int p2m_init(struct domain *d)
{
@@ -32,6 +110,8 @@ int p2m_init(struct domain *d)
# error "Add init of p2m->clean_pte"
#endif
+ p2m_root_order = get_order_from_bytes(GUEST_ROOT_PAGE_TABLE_SIZE);
+
return 0;
}
@@ -42,10 +122,20 @@ int p2m_init(struct domain *d)
*/
int p2m_set_allocation(struct domain *d, unsigned long pages, bool *preempted)
{
+ struct p2m_domain *p2m = p2m_get_hostp2m(d);
int rc;
if ( (rc = paging_freelist_init(d, pages, preempted)) )
return rc;
+ /*
+ * First, initialize p2m pool. Then allocate the root
+ * table so that the necessary pages can be returned from the p2m pool,
+ * since the root table must be allocated using alloc_domheap_pages(...)
+ * to meet its specific requirements.
+ */
+ if ( !p2m->root )
+ p2m_alloc_root_table(p2m);
+
return 0;
}
diff --git a/xen/arch/riscv/paging.c b/xen/arch/riscv/paging.c
index 8882be5ac9..bbe1186900 100644
--- a/xen/arch/riscv/paging.c
+++ b/xen/arch/riscv/paging.c
@@ -54,6 +54,36 @@ int paging_freelist_init(struct domain *d, unsigned long
pages,
return 0;
}
+
+bool paging_ret_pages_to_domheap(struct domain *d, unsigned int nr_pages)
+{
+ struct page_info *page;
+
+ ASSERT(spin_is_locked(&d->arch.paging.lock));
+
+ if ( ACCESS_ONCE(d->arch.paging.total_pages) < nr_pages )
+ return false;
+
+ for ( unsigned int i = 0; i < nr_pages; i++ )
+ {
+ /* Return memory to domheap. */
+ page = page_list_remove_head(&d->arch.paging.freelist);
+ if( page )
+ {
+ ACCESS_ONCE(d->arch.paging.total_pages)--;
+ free_domheap_page(page);
+ }
+ else
+ {
+ printk(XENLOG_ERR
+ "Failed to free P2M pages, P2M freelist is empty.\n");
+ return false;
+ }
+ }
+
+ return true;
+}
+
/* Domain paging struct initialization. */
int paging_domain_init(struct domain *d)
{
--
2.50.1
