#include <palacios/vm_guest_mem.h>
#include <palacios/vm_guest.h>
-
+// Reference: AMD Software Developer Manual Vol.2 Ch.5 "Page Translation and Protection"
static inline int handle_passthrough_pagefault_64(struct guest_info * info,
addr_t fault_addr,
pf_error_t error_code) {
- pml4e64_t * pml = NULL;
- pdpe64_t * pdpe = NULL;
- pde64_t * pde = NULL;
- pte64_t * pte = NULL;
- addr_t host_addr = 0;
-
- int pml_index = PML4E64_INDEX(fault_addr);
+ pml4e64_t * pml = NULL;
+ pdpe64_t * pdpe = NULL;
+ pde64_t * pde = NULL;
+ pde64_2MB_t * pde2mb = NULL;
+ pte64_t * pte = NULL;
+ addr_t host_addr = 0;
+
+ int pml_index = PML4E64_INDEX(fault_addr);
int pdpe_index = PDPE64_INDEX(fault_addr);
- int pde_index = PDE64_INDEX(fault_addr);
- int pte_index = PTE64_INDEX(fault_addr);
-
-
-
+ int pde_index = PDE64_INDEX(fault_addr);
+ int pte_index = PTE64_INDEX(fault_addr);
struct v3_mem_region * region = v3_get_mem_region(info->vm_info, info->cpu_id, fault_addr);
-
+ struct v3_mem_region * base_reg = &(info->vm_info->mem_map.base_region);
+
+ /* If the guest has been configured for 2MiB pages, then we must check for hooked regions of
+ * memory which may overlap with the 2MiB page containing the faulting address (due to
+ * potentially differing access policies in place for e.g. i/o devices and APIC). A 2MiB page
+ * can be used if a) no region overlaps the page [or b) a region does overlap but fully contains
+ * the page]. The [bracketed] text pertains to the #if 0'd code below, state D. TODO modify this
+ * note if someone decides to enable this optimization. It can be tested with the SeaStar
+ * mapping.
+ *
+ * Examples: (CAPS regions are returned by v3_get_next_mem_region; state A returns the base reg)
+ *
+ * |region| |region| 2MiB mapped (state A)
+ * |reg| |REG| 2MiB mapped (state B)
+ * |region| |reg| |REG| |region| |reg| 4KiB mapped (state C)
+ * |reg| |reg| |--REGION---| [2MiB mapped (state D)]
+ * |--------------------------------------------| RAM
+ * ^ fault addr
+ * |----|----|----|----|----|page|----|----|----| 2MB pages
+ * >>>>>>>>>>>>>>>>>>>> search space
+ */
+ addr_t pg_start = 0UL, pg_end = 0UL; // 2MiB page containing the faulting address
+ struct v3_mem_region * pg_next_reg = NULL; // next immediate mem reg after page start addr
+ bool use_large_page = false;
+
if (region == NULL) {
- PrintError("Invalid region in passthrough page fault 64, addr=%p\n",
- (void *)fault_addr);
+ PrintError("%s: invalid region, addr=%p\n", __FUNCTION__, (void *)fault_addr);
return -1;
}
+ // set use_large_page here
+ if (info->vm_info->paging_size == PAGING_2MB) {
+
+ // guest page maps to a host page + offset (so when we shift, it aligns with a host page)
+ pg_start = PAGE_ADDR_2MB(fault_addr);
+ pg_end = (pg_start + PAGE_SIZE_2MB);
+
+ PrintDebug("%s: page [%p,%p) contains address\n", __FUNCTION__, (void *)pg_start, (void *)pg_end);
+
+ pg_next_reg = v3_get_next_mem_region(info->vm_info, info->cpu_id, pg_start);
+
+ if (pg_next_reg == NULL) {
+ PrintError("%s: Error: address not in base region, %p\n", __FUNCTION__, (void *)fault_addr);
+ return -1;
+ }
+
+ if ((pg_next_reg->guest_start == base_reg->guest_start) &&
+ (pg_next_reg->guest_end == base_reg->guest_end)) { // next region == base region
+ use_large_page = 1; // State A
+ } else {
+#if 0 // State B/C and D optimization
+ use_large_page = (pg_next_reg->guest_end >= pg_end) &&
+ ((pg_next_reg->guest_start >= pg_end) || (pg_next_reg->guest_start <= pg_start));
+ PrintDebug("%s: region [%p,%p) %s partial overlap with page\n", __FUNCTION__,
+ (void *)pg_next_reg->guest_start, (void *)pg_next_reg->guest_end,
+ (use_large_page ? "does not have" : "has"));
+#else // State B/C
+ use_large_page = (pg_next_reg->guest_start >= pg_end);
+ PrintDebug("%s: region [%p,%p) %s overlap with page\n", __FUNCTION__,
+ (void *)pg_next_reg->guest_start, (void *)pg_next_reg->guest_end,
+ (use_large_page ? "does not have" : "has"));
+#endif
+ }
+ }
+
+ PrintDebug("%s: Address gets a 2MiB page? %s\n", __FUNCTION__, (use_large_page ? "yes" : "no"));
+
// Lookup the correct PML address based on the PAGING MODE
if (info->shdw_pg_mode == SHADOW_PAGING) {
pml = CR3_TO_PML4E64_VA(info->ctrl_regs.cr3);
pml[pml_index].writable = 1;
pml[pml_index].user_page = 1;
- pml[pml_index].pdp_base_addr = PAGE_BASE_ADDR((addr_t)V3_PAddr(pdpe));
+ pml[pml_index].pdp_base_addr = PAGE_BASE_ADDR_4KB((addr_t)V3_PAddr(pdpe));
} else {
- pdpe = V3_VAddr((void*)BASE_TO_PAGE_ADDR(pml[pml_index].pdp_base_addr));
+ pdpe = V3_VAddr((void*)BASE_TO_PAGE_ADDR_4KB(pml[pml_index].pdp_base_addr));
}
// Fix up the PDPE entry
pdpe[pdpe_index].writable = 1;
pdpe[pdpe_index].user_page = 1;
- pdpe[pdpe_index].pd_base_addr = PAGE_BASE_ADDR((addr_t)V3_PAddr(pde));
+ pdpe[pdpe_index].pd_base_addr = PAGE_BASE_ADDR_4KB((addr_t)V3_PAddr(pde));
} else {
- pde = V3_VAddr((void*)BASE_TO_PAGE_ADDR(pdpe[pdpe_index].pd_base_addr));
+ pde = V3_VAddr((void*)BASE_TO_PAGE_ADDR_4KB(pdpe[pdpe_index].pd_base_addr));
+ }
+
+ // Fix up the 2MiB PDE and exit here
+ if (use_large_page) {
+
+ pde2mb = (pde64_2MB_t *)pde; // all but these two lines are the same for PTE
+ pde2mb[pde_index].large_page = 1;
+
+ if (pde2mb[pde_index].present == 0) {
+ pde2mb[pde_index].user_page = 1;
+
+ if ((region->flags.alloced == 1) && (region->flags.read == 1)) {
+ // Full access
+ pde2mb[pde_index].present = 1;
+
+ if (region->flags.write == 1) {
+ pde2mb[pde_index].writable = 1;
+ } else {
+ pde2mb[pde_index].writable = 0;
+ }
+
+ if (v3_gpa_to_hpa(info, fault_addr, &host_addr) == -1) {
+ PrintError("Error Could not translate fault addr (%p)\n", (void *)fault_addr);
+ return -1;
+ }
+
+ pde2mb[pde_index].page_base_addr = PAGE_BASE_ADDR_2MB(host_addr);
+ } else {
+ return region->unhandled(info, fault_addr, fault_addr, region, error_code);
+ }
+ } else {
+ // We fix all permissions on the first pass,
+ // so we only get here if its an unhandled exception
+
+ return region->unhandled(info, fault_addr, fault_addr, region, error_code);
+ }
}
+ // Continue with the 4KiB page heirarchy
// Fix up the PDE entry
if (pde[pde_index].present == 0) {
pde[pde_index].writable = 1;
pde[pde_index].user_page = 1;
- pde[pde_index].pt_base_addr = PAGE_BASE_ADDR((addr_t)V3_PAddr(pte));
+ pde[pde_index].pt_base_addr = PAGE_BASE_ADDR_4KB((addr_t)V3_PAddr(pte));
} else {
- pte = V3_VAddr((void*)BASE_TO_PAGE_ADDR(pde[pde_index].pt_base_addr));
+ pte = V3_VAddr((void*)BASE_TO_PAGE_ADDR_4KB(pde[pde_index].pt_base_addr));
}
return -1;
}
- pte[pte_index].page_base_addr = PAGE_BASE_ADDR(host_addr);
+ pte[pte_index].page_base_addr = PAGE_BASE_ADDR_4KB(host_addr);
} else {
return region->unhandled(info, fault_addr, fault_addr, region, error_code);
}
if (pdpe[pdpe_index].present == 0) {
return 0;
- } else if (pdpe[pdpe_index].large_page == 1) {
+ } else if (pdpe[pdpe_index].large_page == 1) { // 1GiB
pdpe[pdpe_index].present = 0;
return 0;
}
if (pde[pde_index].present == 0) {
return 0;
- } else if (pde[pde_index].large_page == 1) {
+ } else if (pde[pde_index].large_page == 1) { // 2MiB
pde[pde_index].present = 0;
return 0;
}
pte = V3_VAddr((void*)BASE_TO_PAGE_ADDR(pde[pde_index].pt_base_addr));
- pte[pte_index].present = 0;
+ pte[pte_index].present = 0; // 4KiB
return 0;
}
