[PATCH v6 1/9] x86/cpu: KVM: Add common defines for architectural memory types (PAT, MTRRs, etc.)

Sean Christopherson
2024-03-09T01:27:33Z

Add defines for the architectural memory types that can be shoved into
various MSRs and registers, e.g. MTRRs, PAT, VMX capabilities MSRs, EPTPs,
etc. While most MSRs/registers support only a subset of all memory types,
the values themselves are architectural and identical across all users.

Leave the goofy MTRR_TYPE_* definitions as-is since they are in a uapi
header, but add compile-time assertions to connect the dots (and sanity
check that the msr-index.h values didn't get fat-fingered).

Keep the VMX_EPTP_MT_* defines so that it's slightly more obvious that the
EPTP holds a single memory type in 3 of its 64 bits; those bits just
happen to be 2:0, i.e. don't need to be shifted.

Opportunistically use X86_MEMTYPE_WB instead of an open coded '6' in
setup_vmcs_config().

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/include/asm/msr-index.h | 15 ++++++++++++++-
arch/x86/include/asm/vmx.h | 5 +++--
arch/x86/kernel/cpu/mtrr/mtrr.c | 6 ++++++
arch/x86/kvm/vmx/nested.c | 2 +-
arch/x86/kvm/vmx/vmx.c | 2 +-
arch/x86/mm/pat/memtype.c | 33 ++++++++++++--------------------
6 files changed, 37 insertions(+), 26 deletions(-)

diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index f1bd7b91b3c6..29f0ea78e41c 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -36,6 +36,20 @@
#define EFER_FFXSR (1<<_EFER_FFXSR)
#define EFER_AUTOIBRS (1<<_EFER_AUTOIBRS)

+/*
+ * Architectural memory types that are common to MTRRs, PAT, VMX MSRs, etc.
+ * Most MSRs support/allow only a subset of memory types, but the values
+ * themselves are common across all relevant MSRs.
+ */
+#define X86_MEMTYPE_UC 0ull /* Uncacheable, a.k.a. Strong Uncacheable */
+#define X86_MEMTYPE_WC 1ull /* Write Combining */
+/* RESERVED 2 */
+/* RESERVED 3 */
+#define X86_MEMTYPE_WT 4ull /* Write Through */
+#define X86_MEMTYPE_WP 5ull /* Write Protected */
+#define X86_MEMTYPE_WB 6ull /* Write Back */
+#define X86_MEMTYPE_UC_MINUS 7ull /* Weak Uncacheabled (PAT only) */
+
/* Intel MSRs. Some also available on other CPUs */

#define MSR_TEST_CTRL 0x00000033
@@ -1108,7 +1122,6 @@
#define VMX_BASIC_64 0x0001000000000000LLU
#define VMX_BASIC_MEM_TYPE_SHIFT 50
#define VMX_BASIC_MEM_TYPE_MASK 0x003c000000000000LLU
-#define VMX_BASIC_MEM_TYPE_WB 6LLU
#define VMX_BASIC_INOUT 0x0040000000000000LLU

/* Resctrl MSRs: */
diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index 0e73616b82f3..4fdc76263066 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -504,9 +504,10 @@ enum vmcs_field {
#define VMX_EPTP_PWL_4 0x18ull
#define VMX_EPTP_PWL_5 0x20ull
#define VMX_EPTP_AD_ENABLE_BIT (1ull << 6)
+/* The EPTP memtype is encoded in bits 2:0, i.e. doesn't need to be shifted. */
#define VMX_EPTP_MT_MASK 0x7ull
-#define VMX_EPTP_MT_WB 0x6ull
-#define VMX_EPTP_MT_UC 0x0ull
+#define VMX_EPTP_MT_WB X86_MEMTYPE_WB
+#define VMX_EPTP_MT_UC X86_MEMTYPE_UC
#define VMX_EPT_READABLE_MASK 0x1ull
#define VMX_EPT_WRITABLE_MASK 0x2ull
#define VMX_EPT_EXECUTABLE_MASK 0x4ull
diff --git a/arch/x86/kernel/cpu/mtrr/mtrr.c b/arch/x86/kernel/cpu/mtrr/mtrr.c
index 767bf1c71aad..125e36010b82 100644
--- a/arch/x86/kernel/cpu/mtrr/mtrr.c
+++ b/arch/x86/kernel/cpu/mtrr/mtrr.c
@@ -55,6 +55,12 @@

#include "mtrr.h"

+static_assert(X86_MEMTYPE_UC == MTRR_TYPE_UNCACHABLE);
+static_assert(X86_MEMTYPE_WC == MTRR_TYPE_WRCOMB);
+static_assert(X86_MEMTYPE_WT == MTRR_TYPE_WRTHROUGH);
+static_assert(X86_MEMTYPE_WP == MTRR_TYPE_WRPROT);
+static_assert(X86_MEMTYPE_WB == MTRR_TYPE_WRBACK);
+
/* arch_phys_wc_add returns an MTRR register index plus this offset. */
#define MTRR_TO_PHYS_WC_OFFSET 1000

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index d05ddf751491..82a35aba7d2b 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -7006,7 +7006,7 @@ static void nested_vmx_setup_basic(struct nested_vmx_msrs *msrs)
VMCS12_REVISION |
VMX_BASIC_TRUE_CTLS |
((u64)VMCS12_SIZE << VMX_BASIC_VMCS_SIZE_SHIFT) |
- (VMX_BASIC_MEM_TYPE_WB << VMX_BASIC_MEM_TYPE_SHIFT);
+ (X86_MEMTYPE_WB << VMX_BASIC_MEM_TYPE_SHIFT);

if (cpu_has_vmx_basic_inout())
msrs->basic |= VMX_BASIC_INOUT;
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 7a74388f9ecf..71cc6e3b3221 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2692,7 +2692,7 @@ static int setup_vmcs_config(struct vmcs_config *vmcs_conf,
#endif

/* Require Write-Back (WB) memory type for VMCS accesses. */
- if (((vmx_msr_high >> 18) & 15) != 6)
+ if (((vmx_msr_high >> 18) & 15) != X86_MEMTYPE_WB)
return -EIO;

rdmsrl(MSR_IA32_VMX_MISC, misc_msr);
diff --git a/arch/x86/mm/pat/memtype.c b/arch/x86/mm/pat/memtype.c
index 0904d7e8e126..3e0ba044925f 100644
--- a/arch/x86/mm/pat/memtype.c
+++ b/arch/x86/mm/pat/memtype.c
@@ -175,15 +175,6 @@ static inline void set_page_memtype(struct page *pg,
}
#endif

-enum {
- PAT_UC = 0, /* uncached */
- PAT_WC = 1, /* Write combining */
- PAT_WT = 4, /* Write Through */
- PAT_WP = 5, /* Write Protected */
- PAT_WB = 6, /* Write Back (default) */
- PAT_UC_MINUS = 7, /* UC, but can be overridden by MTRR */
-};
-
#define CM(c) (_PAGE_CACHE_MODE_ ## c)

static enum page_cache_mode __init pat_get_cache_mode(unsigned int pat_val,
@@ -193,13 +184,13 @@ static enum page_cache_mode __init pat_get_cache_mode(unsigned int pat_val,
char *cache_mode;

switch (pat_val) {
- case PAT_UC: cache = CM(UC); cache_mode = "UC "; break;
- case PAT_WC: cache = CM(WC); cache_mode = "WC "; break;
- case PAT_WT: cache = CM(WT); cache_mode = "WT "; break;
- case PAT_WP: cache = CM(WP); cache_mode = "WP "; break;
- case PAT_WB: cache = CM(WB); cache_mode = "WB "; break;
- case PAT_UC_MINUS: cache = CM(UC_MINUS); cache_mode = "UC- "; break;
- default: cache = CM(WB); cache_mode = "WB "; break;
+ case X86_MEMTYPE_UC: cache = CM(UC); cache_mode = "UC "; break;
+ case X86_MEMTYPE_WC: cache = CM(WC); cache_mode = "WC "; break;
+ case X86_MEMTYPE_WT: cache = CM(WT); cache_mode = "WT "; break;
+ case X86_MEMTYPE_WP: cache = CM(WP); cache_mode = "WP "; break;
+ case X86_MEMTYPE_WB: cache = CM(WB); cache_mode = "WB "; break;
+ case X86_MEMTYPE_UC_MINUS: cache = CM(UC_MINUS); cache_mode = "UC- "; break;
+ default: cache = CM(WB); cache_mode = "WB "; break;
}

memcpy(msg, cache_mode, 4);
@@ -254,11 +245,11 @@ void pat_cpu_init(void)
void __init pat_bp_init(void)
{
struct cpuinfo_x86 *c = &boot_cpu_data;
-#define PAT(p0, p1, p2, p3, p4, p5, p6, p7) \
- (((u64)PAT_ ## p0) | ((u64)PAT_ ## p1 << 8) | \
- ((u64)PAT_ ## p2 << 16) | ((u64)PAT_ ## p3 << 24) | \
- ((u64)PAT_ ## p4 << 32) | ((u64)PAT_ ## p5 << 40) | \
- ((u64)PAT_ ## p6 << 48) | ((u64)PAT_ ## p7 << 56))
+#define PAT(p0, p1, p2, p3, p4, p5, p6, p7) \
+ ((X86_MEMTYPE_ ## p0) | (X86_MEMTYPE_ ## p1 << 8) | \
+ (X86_MEMTYPE_ ## p2 << 16) | (X86_MEMTYPE_ ## p3 << 24) | \
+ (X86_MEMTYPE_ ## p4 << 32) | (X86_MEMTYPE_ ## p5 << 40) | \
+ (X86_MEMTYPE_ ## p6 << 48) | (X86_MEMTYPE_ ## p7 << 56))

if (!IS_ENABLED(CONFIG_X86_PAT))
--
2.44.0.278.ge034bb2e1d-goog