[PATCH v4 4/6] Drivers: hv: Mark shared memory as decrypted for CCA Realms
flat view
COOLING5d
REVIEWED: 1 (0M)
From: Kameron Carr <hidden>
Date: 2026-10-01 22:07:01
Also in:
linux-arch, linux-arm-kernel, lkml
Subsystem:
arm64 port (aarch64 architecture), generic include/asm header files, hyper-v/azure core and drivers, the rest · Maintainers:
Catalin Marinas, Will Deacon, Arnd Bergmann, "K. Y. Srinivasan", Haiyang Zhang, Wei Liu, Dexuan Cui, Long Li, Linus Torvalds
Revision v4 of 5 in this series; 1 review trailer.
Revisions (5)
In hv_common_cpu_init(), the per-CPU hypercall input/output pages need to be marked as decrypted (shared) for confidential VM isolation types. This is already done for SNP and TDX isolation; extend the same handling to Arm CCA Realm guests so that the host hypervisor can access the shared hypercall buffers. is_realm_world() is only declared in arch/arm64/include/asm/rsi.h, so using it directly in the arch-neutral drivers/hv/hv_common.c would break the x86 build. Introduce a Hyper-V-specific helper following the established hv_isolation_type_snp() / hv_isolation_type_tdx() pattern. On architectures other than arm64 the weak default keeps the existing behaviour. Reviewed-by: Michael Kelley <redacted> Signed-off-by: Kameron Carr <redacted> --- arch/arm64/hyperv/mshyperv.c | 5 +++++ drivers/hv/hv_common.c | 17 +++++++++++++---- include/asm-generic/mshyperv.h | 1 + 3 files changed, 19 insertions(+), 4 deletions(-)
diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c
index b1657cf..45ca8e2 100644
--- a/arch/arm64/hyperv/mshyperv.c
+++ b/arch/arm64/hyperv/mshyperv.c@@ -158,3 +158,8 @@ bool hv_is_hyperv_initialized(void) return hyperv_initialized; } EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized); + +bool hv_isolation_type_cca(void) +{ + return is_realm_world(); +}
diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
index 31256cb..a60c92c 100644
--- a/drivers/hv/hv_common.c
+++ b/drivers/hv/hv_common.c@@ -476,6 +476,7 @@ int hv_common_cpu_init(unsigned int cpu) u64 msr_vp_index; gfp_t flags; const int pgcount = hv_output_page_exists() ? 2 : 1; + const size_t alloc_size = ALIGN((size_t)pgcount * HV_HYP_PAGE_SIZE, PAGE_SIZE); void *mem; int ret = 0;
@@ -489,7 +490,7 @@ int hv_common_cpu_init(unsigned int cpu) * online and then taken offline */ if (!*inputarg) { - mem = kmalloc_array(pgcount, HV_HYP_PAGE_SIZE, flags); + mem = kmalloc(alloc_size, flags); if (!mem) return -ENOMEM;
@@ -499,14 +500,16 @@ int hv_common_cpu_init(unsigned int cpu) } if (!ms_hyperv.paravisor_present && - (hv_isolation_type_snp() || hv_isolation_type_tdx())) { - ret = set_memory_decrypted((unsigned long)mem, pgcount); + (hv_isolation_type_snp() || hv_isolation_type_tdx() || + hv_isolation_type_cca())) { + ret = set_memory_decrypted((unsigned long)mem, + alloc_size >> PAGE_SHIFT); if (ret) { /* It may be unsafe to free 'mem' */ return ret; } - memset(mem, 0x00, pgcount * HV_HYP_PAGE_SIZE); + memset(mem, 0x00, alloc_size); } /*
@@ -666,6 +669,12 @@ bool __weak hv_isolation_type_tdx(void) } EXPORT_SYMBOL_GPL(hv_isolation_type_tdx); +bool __weak hv_isolation_type_cca(void) +{ + return false; +} +EXPORT_SYMBOL_GPL(hv_isolation_type_cca); + void __weak hv_setup_vmbus_handler(void (*handler)(void)) { }
diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index bf601d6..1fa79ab 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h@@ -79,6 +79,7 @@ u64 hv_do_fast_hypercall16(u16 control, u64 input1, u64 input2); bool hv_isolation_type_snp(void); bool hv_isolation_type_tdx(void); +bool hv_isolation_type_cca(void); /* * On architectures where Hyper-V doesn't support AEOI (e.g., ARM64),
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2.45.4