Re: [kvm-unit-tests PATCH v2 2/4] x86: Remove redeundant page zeroing

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On 05/03/2019 03:32 AM, nadav.amit@xxxxxxxxx wrote:

From: Nadav Amit <nadav.amit@xxxxxxxxx>

Now that alloc_page() zeros the page, remove the redundant page zeroing.

Suggested-by: Andrew Jones <drjones@xxxxxxxxxx>
Signed-off-by: Nadav Amit <nadav.amit@xxxxxxxxx>
---
  lib/x86/intel-iommu.c    |  5 -----
  x86/eventinj.c           |  1 -
  x86/hyperv_connections.c |  4 ----
  x86/vmx.c                | 10 ----------
  x86/vmx_tests.c          | 11 -----------
  5 files changed, 31 deletions(-)

diff --git a/lib/x86/intel-iommu.c b/lib/x86/intel-iommu.c
index 3f3f211..c811ba5 100644
--- a/lib/x86/intel-iommu.c
+++ b/lib/x86/intel-iommu.c
@@ -125,7 +125,6 @@ static void vtd_setup_root_table(void)
  {
  	void *root = alloc_page();
- memset(root, 0, PAGE_SIZE); 
  	vtd_writeq(DMAR_RTADDR_REG, virt_to_phys(root));
  	vtd_gcmd_or(VTD_GCMD_ROOT);
  	printf("DMAR table address: %#018lx\n", vtd_root_table());
@@ -135,7 +134,6 @@ static void vtd_setup_ir_table(void)
  {
  	void *root = alloc_page();
- memset(root, 0, PAGE_SIZE); 
  	/* 0xf stands for table size (2^(0xf+1) == 65536) */
  	vtd_writeq(DMAR_IRTA_REG, virt_to_phys(root) | 0xf);
  	vtd_gcmd_or(VTD_GCMD_IR_TABLE);
@@ -153,7 +151,6 @@ static void vtd_install_pte(vtd_pte_t *root, iova_t iova,
  		offset = PGDIR_OFFSET(iova, level);
  		if (!(root[offset] & VTD_PTE_RW)) {
  			page = alloc_page();
-			memset(page, 0, PAGE_SIZE);
  			root[offset] = virt_to_phys(page) | VTD_PTE_RW;
  		}
  		root = (uint64_t *)(phys_to_virt(root[offset] &
@@ -195,7 +192,6 @@ void vtd_map_range(uint16_t sid, iova_t iova, phys_addr_t pa, size_t size)
if (!re->present) { 
  		ce = alloc_page();
-		memset(ce, 0, PAGE_SIZE);
  		memset(re, 0, sizeof(*re));
  		re->context_table_p = virt_to_phys(ce) >> VTD_PAGE_SHIFT;
  		re->present = 1;
@@ -209,7 +205,6 @@ void vtd_map_range(uint16_t sid, iova_t iova, phys_addr_t pa, size_t size)
if (!ce->present) { 
  		slptptr = alloc_page();
-		memset(slptptr, 0, PAGE_SIZE);
  		memset(ce, 0, sizeof(*ce));
  		/* To make it simple, domain ID is the same as SID */
  		ce->domain_id = sid;
diff --git a/x86/eventinj.c b/x86/eventinj.c
index 250537b..5a07afe 100644
--- a/x86/eventinj.c
+++ b/x86/eventinj.c
@@ -403,7 +403,6 @@ int main(void)
pt = alloc_page(); 
  	cr3 = (void*)read_cr3();
-	memset(pt, 0, 4096);
  	/* use shadowed stack during interrupt delivery */
  	for (i = 0; i < 4096/sizeof(ulong); i++) {
  		if (!cr3[i]) {
diff --git a/x86/hyperv_connections.c b/x86/hyperv_connections.c
index 5d541c9..8eade41 100644
--- a/x86/hyperv_connections.c
+++ b/x86/hyperv_connections.c
@@ -47,7 +47,6 @@ static void setup_hypercall(void)
  	hypercall_page = alloc_page();
  	if (!hypercall_page)
  		report_abort("failed to allocate hypercall page");
-	memset(hypercall_page, 0, PAGE_SIZE);
wrmsr(HV_X64_MSR_GUEST_OS_ID, guestid); @@ -105,9 +104,6 @@ static void setup_cpu(void *ctx) 
  	hv->post_msg = alloc_page();
  	if (!hv->msg_page || !hv->evt_page || !hv->post_msg)
  		report_abort("failed to allocate synic pages for vcpu");
-	memset(hv->msg_page, 0, sizeof(*hv->msg_page));
-	memset(hv->evt_page, 0, sizeof(*hv->evt_page));
-	memset(hv->post_msg, 0, sizeof(*hv->post_msg));
  	hv->msg_conn = MSG_CONN_BASE + vcpu;
  	hv->evt_conn = EVT_CONN_BASE + vcpu;
diff --git a/x86/vmx.c b/x86/vmx.c 
index be47800..962ec0f 100644
--- a/x86/vmx.c
+++ b/x86/vmx.c
@@ -353,7 +353,6 @@ static void test_vmwrite_vmread(void)
  	struct vmcs *vmcs = alloc_page();
  	u32 vmcs_enum_max, max_index = 0;
- memset(vmcs, 0, PAGE_SIZE); 
  	vmcs->hdr.revision_id = basic.revision;
  	assert(!vmcs_clear(vmcs));
  	assert(!make_vmcs_current(vmcs));
@@ -373,7 +372,6 @@ static void test_vmcs_high(void)
  {
  	struct vmcs *vmcs = alloc_page();
- memset(vmcs, 0, PAGE_SIZE); 
  	vmcs->hdr.revision_id = basic.revision;
  	assert(!vmcs_clear(vmcs));
  	assert(!make_vmcs_current(vmcs));
@@ -400,7 +398,6 @@ static void test_vmcs_lifecycle(void)
for (i = 0; i < ARRAY_SIZE(vmcs); i++) { 
  		vmcs[i] = alloc_page();
-		memset(vmcs[i], 0, PAGE_SIZE);
  		vmcs[i]->hdr.revision_id = basic.revision;
  	}
@@ -647,7 +644,6 @@ static void test_vmclear_flushing(void) for (i = 0; i < ARRAY_SIZE(vmcs); i++) { 
  		vmcs[i] = alloc_page();
-		memset(vmcs[i], 0, PAGE_SIZE);
  	}
vmcs[0]->hdr.revision_id = basic.revision; 
@@ -745,7 +741,6 @@ static void split_large_ept_entry(unsigned long *ptep, int level)
new_pt = alloc_page(); 
  	assert(new_pt);
-	memset(new_pt, 0, PAGE_SIZE);
prototype = pte & ~EPT_ADDR_MASK; 
  	if (level == 2)
@@ -1220,7 +1215,6 @@ static void init_vmcs_guest(void)
  static int init_vmcs(struct vmcs **vmcs)
  {
  	*vmcs = alloc_page();
-	memset(*vmcs, 0, PAGE_SIZE);
  	(*vmcs)->hdr.revision_id = basic.revision;
  	/* vmclear first to init vmcs */
  	if (vmcs_clear(*vmcs)) {
@@ -1259,7 +1253,6 @@ static void init_vmx(void)
  	ulong fix_cr4_set, fix_cr4_clr;
vmxon_region = alloc_page(); 
-	memset(vmxon_region, 0, PAGE_SIZE);
vmcs_root = alloc_page(); @@ -1291,9 +1284,7 @@ static void init_vmx(void) 
  	*vmxon_region = basic.revision;
guest_stack = alloc_page(); 
-	memset(guest_stack, 0, PAGE_SIZE);
  	guest_syscall_stack = alloc_page();
-	memset(guest_syscall_stack, 0, PAGE_SIZE);
  }
static void do_vmxon_off(void *data) 
@@ -1420,7 +1411,6 @@ static void test_vmptrst(void)
  	struct vmcs *vmcs1, *vmcs2;
vmcs1 = alloc_page(); 
-	memset(vmcs1, 0, PAGE_SIZE);
  	init_vmcs(&vmcs1);
  	ret = vmcs_save(&vmcs2);
  	report("test vmptrst", (!ret) && (vmcs1 == vmcs2));
diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
index 2d6b12d..c52ebc6 100644
--- a/x86/vmx_tests.c
+++ b/x86/vmx_tests.c
@@ -253,7 +253,6 @@ static void msr_bmp_init(void)
  	u32 ctrl_cpu0;
msr_bitmap = alloc_page(); 
-	memset(msr_bitmap, 0x0, PAGE_SIZE);
  	ctrl_cpu0 = vmcs_read(CPU_EXEC_CTRL0);
  	ctrl_cpu0 |= CPU_MSR_BITMAP;
  	vmcs_write(CPU_EXEC_CTRL0, ctrl_cpu0);
@@ -627,8 +626,6 @@ static int iobmp_init(struct vmcs *vmcs)
io_bitmap_a = alloc_page(); 
  	io_bitmap_b = alloc_page();
-	memset(io_bitmap_a, 0x0, PAGE_SIZE);
-	memset(io_bitmap_b, 0x0, PAGE_SIZE);
  	ctrl_cpu0 = vmcs_read(CPU_EXEC_CTRL0);
  	ctrl_cpu0 |= CPU_IO_BITMAP;
  	ctrl_cpu0 &= (~CPU_IO);
@@ -1062,8 +1059,6 @@ static int setup_ept(bool enable_ad)
  	if (__setup_ept(virt_to_phys(pml4), enable_ad))
  		return 1;
- memset(pml4, 0, PAGE_SIZE); 
-
  	end_of_memory = fwcfg_get_u64(FW_CFG_RAM_SIZE);
  	if (end_of_memory < (1ul << 32))
  		end_of_memory = (1ul << 32);
@@ -1135,8 +1130,6 @@ static int ept_init_common(bool have_ad)
  		return VMX_TEST_EXIT;
  	data_page1 = alloc_page();
  	data_page2 = alloc_page();
-	memset(data_page1, 0x0, PAGE_SIZE);
-	memset(data_page2, 0x0, PAGE_SIZE);
  	*((u32 *)data_page1) = MAGIC_VAL_1;
  	*((u32 *)data_page2) = MAGIC_VAL_2;
  	install_ept(pml4, (unsigned long)data_page1, (unsigned long)data_page2,
@@ -1483,7 +1476,6 @@ static int pml_init(struct vmcs *vmcs)
  	}
pml_log = alloc_page(); 
-	memset(pml_log, 0x0, PAGE_SIZE);
  	vmcs_write(PMLADDR, (u64)pml_log);
  	vmcs_write(GUEST_PML_INDEX, PML_INDEX - 1);
@@ -1908,9 +1900,6 @@ static int msr_switch_init(struct vmcs *vmcs) 
  	exit_msr_store = alloc_page();
  	exit_msr_load = alloc_page();
  	entry_msr_load = alloc_page();
-	memset(exit_msr_store, 0, PAGE_SIZE);
-	memset(exit_msr_load, 0, PAGE_SIZE);
-	memset(entry_msr_load, 0, PAGE_SIZE);
  	entry_msr_load[0].index = MSR_KERNEL_GS_BASE;
  	entry_msr_load[0].value = MSR_MAGIC;


Reviewed-by: Krish Sadhukhan <krish.sadhukhan@xxxxxxxxxx>
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